Rainwater Harvesting Systems: A Sustainable Solution for Water Conservation

Explore our comprehensive FAQs portal dedicated to rainwater harvesting systems, an innovative approach to water conservation. Discover how these systems collect and store rainwater from rooftops, enabling you to reduce your reliance on traditional water sources. Learn about the various components involved, including storage tanks, filtration systems, and distribution methods. Gain valuable insights into the benefits of rainwater harvesting, such as reduced water bills, improved landscape irrigation, and mitigating stormwater runoff. Whether you’re a homeowner or a business owner, this guide will equip you with the knowledge to implement a sustainable water management strategy for a greener future.

Why bury a rainwater tank instead of using an above ground tank that can be more easily maintained?

An aboveground rainwater harvesting tank is easier to install and maintain, and it may be more cost-effective. However, there are advantages to burying the tank underground. Firstly, being underground provides a controlled environment that minimises UV exposure and temperature fluctuations, preventing the growth of microorganisms. Secondly, an underground tank saves space as it can be installed discreetly in a garden or driveway, allowing other uses like parking. It offers a more integrated solution. Additionally, the maintenance of underground tanks, like the ECO-Plus system, can be facilitated by external control elements. It’s essential to consider all options and choose a rainwater harvesting solution that best suits your specific requirements and desired applications. Proper understanding and consideration will lead to a more suitable and satisfactory choice.

What is the maximum distance a pump can be from a house?

When it comes to the maximum distance a pump can be located from the property, it depends on the type of pump being used.

For submersible pumps that are installed within an underground tank, they typically have good pressure and flow rates. Most domestic submersible pumps can handle 4,000 litres per hour or more, which is about one to one and a half litres per second. With a 40-meter head of pressure, you can generally expect a range of up to 40 meters vertically or 400 meters horizontally, although there may be some variations due to pipe work.

For most domestic rainwater harvesting systems, a submersible pump is sufficient to supply water over considerable distances. However, it’s important to note that if multiple outlet connections are open simultaneously, there may be a slight drop in pressure and flow rate, favouring the closest outlet.

Considering typical property heights and the possibility of pumping water back into the property for different applications, it is feasible to have a property located around 300 meters away from the underground tank.

It’s worth mentioning that if you have a wall-mounted pump console inside the property, the underground tank should be located closer to the console. This is because the pump console relies on sufficient power to draw water from the underground tank. The 40-metre head of pressure provided by the pump can still push the water over long distances, but the proximity between the tank and the wall-mounted console needs to be considered more carefully.

Is rainwater harvesting illegal?

No, rainwater harvesting is not illegal in the UK. In fact, it is encouraged by councils and there are regulations in place to ensure its safe and proper usage. However, it’s important to consider health and safety aspects such as preventing cross-contamination between rainwater and mains water. Labelling rainwater outlets is recommended, especially in internal systems where accidental consumption by children may occur. It’s worth noting that while rainwater harvesting is legal in the UK, there may be misconceptions due to certain US states where it is restricted or prohibited. But in the UK, you can confidently pursue rainwater harvesting without any legal issues.

How do I access the water in my underground tank for the garden?

With the Graf system, accessing the water in your underground tank for the garden is made easy. You have multiple options for external connection points, such as plumbing for outside bib taps, internal hose connection points, tap pillars, and even connections to fountains. The pump in the tank operates when there’s a demand for water, and you can connect multiple outlets simultaneously, considering the flow rates. The design of your project will determine the placement of outlet points, whether it’s at the front, back, or even remote locations in the garden. The standard garden comfort package includes an internal hose connection box, and there’s also the option for an external hose connection box placed farther down the garden. These accessories can be added on to suit your specific needs. Tap pillars are available in plastic and stainless steel, offering a wide range of choices to extract water from your tank easily.

Can the underground tank be connected to an external tap?

Yes, the underground tank can be connected to an external tap. The primary application for rainwater harvest systems is outside irrigation, allowing you to easily water your plants with rainwater. Installing an outside bib tap is straightforward, with a feed line connected to the pump in the underground tank. When you turn on the tap, water is supplied, and when you turn it off, the system shuts off. This setup is not only useful for garden irrigation but can also be used for tasks like washing your car or cleaning external surfaces. It’s a convenient and effective solution for various external water needs.

Can the rainwater tank be connected to garden irrigation system?

Yes, the rainwater tank can be connected to a garden irrigation system. This is a common and desirable application for rainwater systems. The irrigation system can include automatic drip feeders and pop-up sprinklers, regulated by a timer box. When the timer activates the irrigation system, the submersible pump in the underground tank detects the drop in pressure, turns on, and supplies water until the timer switches off. The pump operates under pressure, similar to other household appliances. It’s an automatic process that provides water for garden irrigation. It’s important to note that if using drip feeder pipes, additional pressure reducing valves may be needed to ensure the system functions as intended.

Can surface water go into a rainwater harvesting tank?

Yes, surface water can be collected in a rainwater harvesting tank, but there are considerations to keep in mind. It is important to determine if the rainwater collected from the roof alone is sufficient for your needs. If it is, there is no need to collect surface water. However, if additional volume is required, surface water can be considered.

When collecting surface water, it is crucial to treat and filter it, as it may contain mixed fuels, oils, or other contaminants. This is especially important if the surface water comes from areas like car parks or driveways. Collecting water from pavement areas or back gardens might be safer as they are less likely to contain vehicle-related pollutants.

Before channeling surface water into your rainwater harvesting tank, carefully assess its source and potential contaminants. Consider the purpose of the water and the amount of rainwater you truly need to harvest. Generally, it is encouraged to rely on roof areas only unless additional volume is necessary.

Can rainwater harvesting help in a drought?

Yes, rainwater harvesting can be a valuable resource during droughts. In a drought, when there is a prolonged lack of rainfall, any water collected through rainwater harvesting becomes an extra supply that would not have been available otherwise. It can help supplement water needs during these dry periods. So, yes, rainwater harvesting can indeed assist during droughts.

Where would the overflow from a rainwater harvesting tank go to?

The overflow from a rainwater harvesting tank can be directed to different places depending on the situation. The two primary options are a soakaway or a storm drain. If the soil has good permeability and there is enough space available, it’s preferable to discharge to a soakaway. However, if the ground conditions are poor or there is no suitable percolation rate, the overflow can be directed to a storm drain.

Graf systems offer specific filters based on the discharge destination. For a soakaway, a basket filter is used to retain leaves and debris. For a storm drain or alternative option, a self-cleaning filter is used to wash the water over the top and prevent leaves and debris from entering the soakaway. The choice of filter depends on the specific discharge destination.

What type of filter do I need for my rainwater harvesting system?

The type of filter you need for your rainwater harvesting system depends on your specific needs and usage. If you’re using the system for gardening purposes only, a basket filter is recommended for efficient filtration and capturing debris. For a household system with higher water demand, a self-cleaning filter is more suitable to ensure continuous filtration. If you’re discharging water into the ground through a soakaway, a basket filter is preferred to retain leaves and debris. The size of the filter is determined by the pipe diameter, which is based on the catchment area. Consider these factors when selecting a filter for your system.

What type of backfill do I need for my tank?

When installing the tank, there are two types of backfill to consider: pea shingle and granular backfill. Pea shingle, with a size of 8 to 16 millimetres, is commonly used and provides good compaction without voids. In the UK, 10 to 20 millimetres is acceptable. Granular backfill is suitable if you have well-draining soil and offers more flexibility in the installation process. Another option is a lean dry mix concrete backfill, which is recommended for challenging soil conditions. The excavation size should allow for working room around the tank, typically 250 to 500 millimetres. If you need advice on available backfill materials in your area, we’re here to help. Stone is preferable, but concrete is also a suitable option if necessary.

What happens during periods of no rainfall and the tank runs out of rainwater?

During periods of no rainfall, if the rainwater tank runs out of water, there are options to ensure a continuous water supply. The system is designed to prevent running out of water, but if it does happen, there is a mains water top-up supply available. This can be achieved through a gravity-fed mains water supply to the underground tank, a direct mains water supply to a loft tank (in the case of a header tank installation), or a modern pump kiosk with a float switch. These mechanisms detect the water level and automatically redirect mains water to the appliances until the underground tank is refilled during the next rainfall event. So, even during periods without rainfall, there is a backup solution in place to provide water to the appliances.

Is a firefighter tank mentioned in any of the UK regulations or mandatory in any specifics schemes?

Firefighter water tanks are mandatory for certain types of projects in the UK. These tanks are essential for providing access to water in case of a fire emergency. Whether it’s a school, supermarket, or hotel complex, there should always be a fire hydrant access point as part of the site’s risk assessment. GRAF offers their own firefighting tanks, which are marked and known to the fire service. Even smaller domestic projects may require an access point for fire engine top-up facilities. The presence of these tanks ensures that there is a readily available water supply for firefighting purposes. While the requirement for firefighter water tanks depends on the project and the availability of a mains water supply, it is important to consider them during the design phase to meet regulatory standards.

How does the float switch work in the tank?

The float switch works in conjunction with a direct feed system to ensure a continuous water supply to the appliances. When the tank has sufficient rainwater, the float switch remains in a vertical position, signaling that rainwater can be supplied on demand. However, if the rainwater level in the tank decreases, the float switch drops, triggering a response. This response varies depending on the system setup, such as a wall-mounted pump kiosk or a submersible pump solution with a mains water top-up unit.

In either case, the float switch controls the automatic flow of rainwater or mains water to ensure a consistent water source for the appliances. It acts as a control mechanism, allowing the customer to always have water available for their needs.

How do I know if my water outlet as a mainswater or rainwater connections?

To identify if a water outlet has a mains water or rainwater connection, there are specific labelling and colour codes to look for. Rainwater outlets should be labeled and marked with black and green colours. For underground pipes, it will typically be a black pipe with a green stripe. Outside taps should have a plaque indicating that it is a non-drinking water source, usually green with black text.

It’s important to note that most mains water taps won’t have any labelling. If there’s no label, it’s likely a mains water connection. However, it’s always a good idea to confirm with the owner or building authority to be sure. When ordering a rainwater harvesting system, there should be sticker kits or labelling packs available to mark the outlets correctly. If these are not provided, you can contact the manufacturer to obtain them. It’s essential to label outlets, especially if there are children living in the property, to prevent accidental consumption of rainwater.

Can I install the tank underneath a driveway?

Yes, it is possible to install a rainwater harvesting system underneath a driveway. With Graf tanks and many other systems available, they are designed to support light-duty traffic loads. It’s important to ensure adequate cover levels over the tank to distribute the load and upgrade the tank cover accordingly.

For light-duty traffic, a vehicle loading lid can be used, while for heavier loads such as HGVs, a specialist installation practice is required. This may involve recessing one of the lids and placing a suitable manhole cover and frame, such as a T400 or higher grade, over it. On domestic properties, installing for light-duty traffic is relatively straightforward. However, for larger construction sites, it may be necessary to grade the system and use a bespoke manhole cover.

Overall, it is feasible to install a rainwater harvesting system under a driveway, but the specific requirements will depend on the load capacity needed and the installation practices followed.

Where can you look about rainwater harvesting if they have questions and want to do more research?

To learn more about rainwater harvesting and find answers to your questions, you can visit our website grafuk.co.uk. Our blog page contains various articles that cover topics such as what rainwater harvesting is, different types of systems (direct or indirect), and more. Additionally, we have a YouTube channel where you can watch videos showcasing how our systems work and gain a better understanding of their benefits and applications. Whether you’re interested in sizing the system, choosing between direct or indirect systems, or simply using rainwater for garden irrigation, our resources will provide you with valuable information to help you make informed decisions.

What can people use harvested rainwater for and can people drink it?

Looking in accordance with the British Standard regulation, you would use the harvested rainwater for toilets, washing machine, outside cleaning, and irrigation. These are the primary uses. You can further treat the water to disinfect it with carbon filters, UV and micro filters. By taking out any impurities in the water, you can reuse it for other possible appliances such as the dishwasher or showers.

Here in the UK, we have the technology to improve on making the water quality better. If we compare it to outside the UK, where they are not so advanced in the more rural locations of the world. Rainwater is most likely the cleanest source of water they can get a hold of, so in their case they will drink it.

Is there a control panel for the rainwater harvesting system?

This depends on the technical package you have. Most systems will run off an automatic pressure-sensitive pump, which will pump water on demand to the application by opening and closing of a valve. The pump will sense the opening of that valve and it will pump water on demand until the valve closes, then it will shut off.

With more advanced systems, we can supply a control panel to give you a bit more in-depth detail of what is going on in terms of the use of the rainwater versus how much mains water you are potentially saving. It can also detect the level of water in the ground tank as well as opening and controlling solenoid valves for automatic cleaning of the filters.

For standard systems, it would be the submersible pump options. Whereas with more advanced systems, you can have a lot more technology with the control system to get a better idea of how efficiently your system is working.

Is the pump on all the time?

With control systems, whether this is a pump console or submersible pump, we would supply power to that 24 hours a day. But it is the operation of the pump, so it turns on via a float sensor built into the pump when the valve is opened. So, the pump is only running whenever you have water running to an outlet. The power is only consumed when the system is in operation, so it is an automatic process. Once the system is turned on, the pump will pump on demand and then will shut off once the valve is closed.

Does the system owner need to maintain the filter, if so how?

There are two types of filters commonly used in rainwater harvesting systems. If the tank discharges into the ground via a soakaway, a basket filter is typically used. Homeowners are advised to open the manhole cover, remove the basket filter, empty the debris into a compost bin, and then replace it back into the tank. It is generally recommended to clean the basket filter every two months, but the frequency may vary depending on the property’s location and surrounding trees.

For stainless steel self-cleaning filters, which are connected to a storm network rather than a soakaway, the buildup is not as long. It is usually recommended to clean these filters every six months. However, homeowners will gain an understanding of the specific cleaning frequency based on their system’s performance over time.

It is also recommended to visually check the filter once a month to ensure its proper functioning. This can be done by opening the manhole cover and inspecting the water levels and the cleanliness of the filter. If cleaning is required, the filter can be easily accessed and lifted using the handle on top.

Can you use a rainwater harvesting system for agricultural purposes?

Yes, you can use a rainwater harvesting system for agricultural purposes. Agriculture has significant water demands, including irrigation, livestock watering, vehicle cleaning, washdown, and even some refining processes. Rainwater harvesting provides a great opportunity for farmers to supplement their water needs and achieve substantial savings.

While domestic rainwater harvesting can save up to 50% of water usage, in agriculture, the savings can reach even higher, up to 80-90%. Considering the large amount of water used in agricultural operations compared to households, the potential water savings are highly significant. Implementing rainwater harvesting in agriculture is a beneficial and practical solution to meet water demands efficiently.

What size water butt do I need?

To determine the size of water butt you need, a good rule of thumb is to aim for at least a hundred days’ worth of water supply, which is a little over three months. To calculate this, consider the size of your watering can and how many times you water your garden each day. For example, if you use a 1-litre watering can and water your garden three times a day, you would need a 300-litre water butt to provide a hundred days’ worth of water.

It’s important to choose a container size that suits your needs. While rainwater harvesting can quickly fill a water butt with just one rainfall event, consider where you will place the container. If you prefer a discreet location, ensure you have enough space to accommodate the size and shape of the water butt. Additionally, think about whether you want a decorative style or a container that can be hidden away when not in use.

One popular option is the Slim Stone Wall tank, which holds 300 litres of water. Despite its slim design, it can fit in tight spaces, allowing you to capture a high yield of rainwater for garden use.

Can you retrofit a rainwater harvesting system to an existing building?

Yes, you can retrofit a rainwater harvesting system to an existing building. If you only plan to use the harvested rainwater for outside irrigation and cleaning, it’s a straightforward installation. You connect the rainwater tank to an outside tap or extraction point.

However, if you want to use the rainwater for appliances like toilets or washing machines, retrofitting is more complex. You need to consider preventing cross-contamination between rainwater and mains water. It’s possible to connect the rainwater system to an outside toilet or garage washing machine, isolating the mains water supply.

Rainwater harvesting systems prioritize the use of rainwater first, with a mains water backup supply activated through a flow sensor from the tank.

Even with a small tank, retrofitting can supplement approximately 25-30% of your mains water usage, providing significant environmental benefits and potentially reducing your mains water bill.

Is rainwater good for plants?

Rainwater is beneficial for plants compared to mains water. It contains natural nitrogen absorbed from the air, which enhances plant growth. In contrast, mains water is chemically treated and contains chlorine and minerals that may not be as good for plants. Rainwater, being closer to nature, provides plants with compounds that are beneficial for their development. So, when it comes to watering plants, rainwater is a better choice.

How can you collect rainwater cheaply?

To collect rainwater cheaply, there are a few simple options. One way is to use a water butt, an aboveground tank available in different sizes and colors, costing around £25-£300. This allows you to store rainwater for years and use it for watering plants or outdoor cleaning with the help of a pump. Another option is to incorporate rainwater collection into sustainable urban drainage systems (SUDs) required for flood prevention in cities. By adding storage capacity to these systems, rainwater can be retained and reused to support green areas. Whether using a water butt or integrating with existing solutions like SUDs, collecting rainwater is an affordable and eco-friendly approach.

Can rainwater be used for showers?

Using rainwater for showers can be a bit complicated. While some countries allow it with specific standards, in the UK, it’s generally advised to filter and purify the water before using it. Rainwater runoff from roofs can contain contaminants like moss, so it’s important to cleanse the water. Filtration systems can remove impurities, and UV purification can further enhance water quality. For uses like showering and sinks that involve direct contact with the skin, deionisation to remove minerals and disinfection are recommended. It’s achievable to use rainwater for showers, but upgrading a standard rainwater harvesting system in the UK ensures better water quality.

How long is rainwater good for?

Wastewater treatment systems require regular maintenance, which can be divided into two areas: servicing and de-sludging. For domestic systems, we recommend an annual servicing visit by an engineer to check the treatment process and component health. Commercial systems may require a minimum of two visits per year due to their larger size and more components. Additional modules, such as phosphorus mitigation, may require three to four visits to ensure compliance with discharge parameters.

The de-sludging interval is determined by the size of the primary catchment chamber. Domestic systems typically require de-sludging every 12 months, while commercial systems may need it every six months or even more frequently. It’s important to conduct the servicing before de-sludging to assess the treatment plant’s performance accurately.

By maintaining a regular servicing schedule and adhering to de-sludging intervals, you can ensure optimal performance and longevity of your treatment plant.

Can discoloration of water incur in a rainwater harvesting tank?

Discolouration is to do with the introduction of impurities into the tank. So with the collection of rainwater off a roof, or potentially if you’re collecting rainwater off a surface, like a patio or pavement, you are channeling that water down into the collection device. Now, depending on how clean that surface is, you’re introducing impurities. It could just be dirt and grits. It could be oil if it’s coming off a car park. With the introduction of these impurities, you are going to discolour the water in the tank. The tank itself, the water that’s in there, should remain clean if the catchment area is clean. So it’s only by introduction of the catchment area that water will become discoloured in the tank.

How to maintain a rain water harvesting filter?

There are two types of filters we would normally offer or see within the market of rainwater harvesting. We would normally use a basket filter if the tank were discharged into the ground via a soakaway. A basket filter will capture all the leaves and debris that runs in from the downpipes into this basket. The buildup of more solid debris in that basket will quickly accumulate. We advise the homeowner to open the manhole cover, lift the basket out and empty it into the compost bin. Replace it back into the tank, ready for the system process to continue. With a basket filter, we recommend anything for up to two months. It depends on where your house is found versus the number of trees, so the buildup on your property might be faster than potentially another homeowner.

If you are looking at one of the stainless-steel self-cleaning filters, these are designed for water to wash over the top and take leaves and debris out of the outflow. It is important with this filter that you connect it to a storm network and not into a soakaway. If it goes to a soakaway, those leaves and debris would block the soakaway every time. This is something to pay attention to. But with the self-cleaning filter, the buildup is not so often and recommend checking every 6 months. But once the customer gets an understanding of how long their system has been in place, they will get an idea of how often it needs to be done.

However, we do recommend a visual check once a month of the filter to be taken out, lifted. The cover is relatively easy to lift off. If you’ve got one of the pedestrians covers, it opens with a torque wrench and then you are able to carry out a visual inspection into the top of the tank. Check water levels and the cleanliness of the filter, if it does need to be washed down, it can be easily reached via the handle on the top of the filter to be taken out and lifted and cleaned.

What is the purpose of rainwater harvesting?

Rainwater harvesting has different meanings globally. In areas without access to mains water, rainwater is a vital resource. In the UK, where mains water is available, rainwater can be used to supplement our water consumption as urban development strains existing systems.

Rainwater harvesting can substitute up to 25% of mains water usage, reducing demand and associated costs. It also helps with mitigating droughts, managing floods, and reducing carbon footprint. Water companies utilize significant energy to treat mains water, resulting in a large carbon footprint. Utilizing rainwater locally can make a substantial difference and contribute to environmental protection.

Rainwater harvesting is a step towards sustainability. While government goals are set for the future, it is important to remember that local actions matter. Each individual’s choice to use rainwater instead of relying solely on mains water has an impact.

Addressing the strain on existing water systems and protecting the environment is crucial. Rainwater harvesting and wastewater treatment solutions can have a positive global impact and contribute to a more sustainable future.

What is the environmental impact of rainwater harvesting?

Rainwater harvesting has several environmental impacts that are worth noting. Firstly, it helps reduce the speed and volume of stormwater runoff, which aids in flood prevention and minimizes erosion. This is particularly important in urban areas with high levels of pavement and concrete. Secondly, rainwater harvesting is beneficial during droughts, as it provides a local water source that eases the strain on reservoirs and supports ecosystems. Thirdly, implementing rainwater harvesting systems in urban areas creates green spaces, promoting habitats for various species and contributing to biodiversity. Additionally, rainwater harvesting significantly reduces mains water demand, resulting in a substantial decrease in the carbon footprint associated with water treatment and supply. By substituting rainwater for mains water, both the manufacturing process and the energy consumption of water firms are reduced. Overall, rainwater harvesting has a positive environmental impact by conserving water resources, mitigating flooding, supporting ecosystems, and reducing carbon emissions.

What is water neutrality?

Water neutrality is a new legislation introduced by Natural England to ensure that new buildings do not strain existing water resources. The goal is to minimise the impact on the environment and maintain water consumption levels from before the development. This involves reducing water usage, reusing water through methods like rainwater harvesting and water recycling, and offsetting by supporting other water-efficient projects. Reduction can be achieved through mindful water usage and the implementation of water-efficient appliances. Reuse involves capturing rainwater or treating wastewater for irrigation purposes. Offset refers to supporting external projects that reduce water demand. Water neutrality aims to protect water resources and promote sustainable development for future generations.