Bin It Don’t Flush It

Why “Bin It, Don’t Flush It”?

Modern wastewater treatment systems, whether a small domestic system or a larger commercial plant, are designed to handle only typical household sewage. In the UK, water companies and environmental agencies promote the mantra “Bin it, don’t flush it,” meaning anything that isn’t human waste or toilet tissue belongs in the bin, not down the loo. This guidance is essential for preventing clogs, protecting your treatment system, and avoiding environmental pollution. Even if you have a GRAF One2Clean domestic treatment plant or a traditional septic tank, flushing the wrong things can lead to costly blockages, damage, or even regulatory issues. In fact, over 60% of sewer flooding incidents are caused by blockages from improper items. These problems that can effect off-grid systems just as well as public sewers.

How your system works

Both sewage treatment systems and septic tanks rely on natural biological processes to break down waste. They are built to treat the wastewater from toilets, sinks, and showers. Essentially water mixed with biodegradable waste (the kind that comes from our bodies or gentle household use). What they aren’t built to handle are rubbish and toxins. Non-biodegradable objects can clog pipes or mechanical parts, and harsh chemicals can kill the beneficial bacteria that make the system work. The result? Your system could back up or fail, causing nasty messes, health hazards, and expensive repairs. Below, we’ll break down what you should and shouldn’t flush or pour into any wastewater system.

The “3 P’s” Rule: Only Flush Pee, Poo and Paper

The only things that belong down your toilet are the 3 P’s: pee, poo and (toilet) paper. Everything else should be disposed of in a rubbish bin. Toilet paper is designed to soften and break apart in water, so it’s safe for plumbing and treatment systems. In contrast, even items that seem similar, like paper towels, tissues, or “flushable” wipes, do not disintegrate the same way.

Why this strict rule? Because wastewater systems can only reliably handle genuine sewage and toilet paper. For example, wet wipes, cotton products, or sanitary items will not break down, they remain intact and can snag on pipes or equipment. Over time they accumulate, often binding together with fats to create obstinate clogs (the infamous “fatbergs”). Water UK estimates that the UK flushes 3.4 billion wet wipes a year, which make up around 94% of the material causing sewer blockages. In short, one rogue item might slip through, but masses of “unflushables” build up hidden blockages that can back sewage up into homes or overflow into the environment.

What NOT to Flush (or Pour) and Why

To protect your wastewater treatment system and avoid blockages or pollution, never flush or pour the following down toilets or drains. These guidelines apply to all systems; septic tanks, domestic treatment plants like GRAF’s One2Clean, and even main sewers, because the underlying issues are the same. In general, only substances with the characteristics of domestic wastewater belong in the system. Anything non-biodegradable, non-compostable, or toxic can spell trouble. Let’s break down the main categories of things to “bin, not flush”:

Wet Wipes and Hygiene Products

Do not flush any kind of wipe, even if the packaging says “flushable” or “biodegradable.” Wipes are a leading cause of pipe clogs, they don’t dissolve like toilet paper and tend to snag and mesh together in pipes. Over time, they can form large mats that block the flow or jam moving parts. In fact, experts warn even “flushable” wipes take far longer to break down than toilet paper and often still contain plastic fibres. In small treatment units, clumps of wipes can restrict oxygen flow and impair the bacteria that treat the waste. Other hygiene products are just as bad. Sanitary towels, tampons, nappies, incontinence pads, condoms, cotton wool, and cotton bud sticks should never be flushed. They are either not biodegradable or will swell and block pipes. Even dental floss should be binned, those long stringy strands tangle into ropey clogs and can contribute to fatbergs.

Cooking Fats, Oils and Food Waste

You should never pour grease, fat, or used cooking oil down the sink or toilet. As they cool, fats and oils solidify and coat the inside of pipes, catching other debris and causing blockages. Grease buildup in sewers is a major contributor to fatbergs when combined with flushed wipes. In a septic tank or small treatment plant, fats can also clog the inlet and outlet or float on top as scum, reducing the tank’s effective volume and potentially clogging drain fields. Always scrape plates and pans into the bin before washing, and collect used cooking oil in a container for proper disposal or recycling. Food scraps should not be ground up or flushed either, especially in systems that aren’t designed with a garbage disposal unit. Avoid flushing any solid food waste, coffee grounds and eggshells. As these can build up as sediment or feed the wrong microbes. In fact, the only food-related substances that should enter your treatment system are the tiny bits that can’t be scraped off plates, anything more should go in your bin or compost. For large volumes of kitchen waste water with grease, say from a commercial kitchen linked to a treatment plant, it’s recommended to use a grease separator trap upstream of the system to protect the main system.

Non-Biodegradable & “Odd Items”

It may seem obvious not to flush rubbish, yet wastewater operators routinely find all sorts of strange items in clogged sewers, from cotton bud sticks to kids’ toys, and even the occasional false teeth. Every bit of rubbish that goes down the drain has to be removed somehow, somewhere, often by manual cleaning after it causes a blockage. In your own septic or treatment unit, any small solid that isn’t sewage will either get caught in the tank (filling it up) or lodge in a pipe. Never flush plastic wrappers, cigarette butts, plasters, chewing gum, hair, or any miscellaneous debris. Cat litter and “bird sand” from pet cages must also stay out of toilets. Even “flushable” cat litter will settle like cement in pipes or tanks. In short, treat your toilet and drains only as wastewater conduits, not as a universal bin. Keep a wastebasket in the bathroom for all those odds and ends, it’s worth the minor effort to avoid a major headache later.

Hazardous or Chemical Substances

Never dispose of chemicals, toxins, or medicines down the drain. This includes things like paints, solvents, acids, oils, fuel, antifreeze, pesticides, herbicides, and any other harsh chemical product. These substances can poison the treatment process by killing the helpful bacteria in your septic or treatment plant, preventing proper breakdown of sewage. For example, pouring strong bleach or anti-bacterial cleaners in large quantities can sterilise a septic tank, leading to sewage not being treated and terrible odours or soakaway failure. Solvents and fuels not only threaten your system’s biology but can also pose fire or explosion risks in closed tanks. Additionally, when you flush chemicals, they can pass through into the environment. Small treatment units are not designed to neutralise hazardous chemicals, those chemicals could end up polluting the groundwater or nearby streams. Medicines and pharmaceuticals should also never be flushed. Drugs like antibiotics, hormones, or painkillers can seep into watercourses, harming wildlife and even showing up in trace amounts in drinking water. As the Eden Rivers Trust notes, medicines flushed down the loo can affect wildlife and water quality, so it’s far better to return unused meds to a pharmacy for safe disposal. The same goes for syringes or sharp objects. Never toss those in the toilet (not only can they jam equipment, they pose a danger to anyone handling the waste). UK advice is clear: take chemicals, old paint, motor oil, etc. to your local household waste recycling centre, and return medications or medical sharps to a chemist or appropriate collection point. By keeping these hazards out of your drains, you protect your system’s health and the wider environment.

Excess Water and Unusual Fluids

Interestingly, even certain clean liquids shouldn’t enter your wastewater treatment system. Rainwater from roofs or drains must not be directed into septic tanks or treatment units. Why? Storm runoff can overwhelm the capacity of your system, it’s like suddenly flooding it with many thousands of litres that it’s not designed to process. This can stir up solids that should settle, pushing untreated waste out to the drain field or outlet. It also cools and dilutes the conditions, making life hard for the sewage-treating bacteria. Similarly, groundwater infiltration (like a leaky septic tank or cracked pipe that lets groundwater in) can overload the system, worth inspecting if you suspect it. Swimming pool water is another no-no: pools contain chlorine and other chemicals that are toxic to treatment bacteria, and draining a pool into your system would flood it way beyond design capacity. If you have to empty a pool or hot tub, follow local guidelines (usually dechlorinate and drain to a storm sewer or disperse in your garden, not into the septic). Large volumes of milk or dairy waste should also be kept out of septic/treatment systems. This one surprises people, but milk has an extremely high Biological Oxygen Demand (BOD); pouring out a lot of expired milk can overwhelm the oxygen supply in a small treatment plant, effectively starving the microbes of air. So, small amounts of dairy down the sink (like rinsing a cereal bowl) are fine, but don’t dump gallons of old milk or into the system. Blood is similar, flushing a little from, say, a minor injury cleanup is okay, but large quantities (like from butchering) are too much load for the system to handle at once. And while we’re at it, animal waste (e.g. contents of cat litter trays or animal bedding) shouldn’t be flushed either; pet waste can carry parasites and adds extra solids, better to bag and bin it.

In summary, if it’s not normal human waste or wastewater, keep it out of your toilet, sinks, and drains. When in doubt, remember: Bin it – don’t flush it! This protects your pipes from clogging and your treatment system from upset. The list above may seem long, but it boils down to common sense: toilets and treatment plants are not magical waste annihilators. They’re built for sewage, nothing more.

Best Practices to “Bin It” and Protect Your System

By now, it’s clear what not to flush, but it helps to have practical steps in place to make compliance easy in daily life. Here are some best practices and tips to keep your wastewater system healthy:

Place Bins in Bathrooms and Kitchen

Make sure every bathroom has a convenient bin for sanitary items, wipes, cotton buds, etc. It sounds obvious, but if there’s no bin, people tend to flush things out of sight. In the kitchen, keep a tub or container for food scraps and another for used cooking oil/grease. When you have a system to catch waste, you remove the temptation to use the drain as a rubbish chute.

Use Septic-Safe Products

Choose cleaning and personal products that are labeled septic-safe or biodegradable. This includes toilet paper (most are fine; avoid any super-thick or cushioned brands that advertise “like a towel” strength, you want it to break down easily). For cleaning toilets, sinks, and showers connected to a private system, opt for non-chlorine, mild cleaners (look for environmentally friendly labels). Avoid automatic toilet bowl tablets that release bleach or other chemicals continuously, these can harm your bacteria. If you need to use a stronger disinfectant or drain cleaner occasionally, try to use it sparingly and in small amounts. Never pour large quantities of chemicals at once. There are also enzyme-based drain maintainers that can help digest minor grease buildup without harsh chemicals. those are generally safe for septic systems.

Educate

Make sure everyone knows the basic rules: only flush the 3 Ps, everything else goes in the bin. This includes children (teach them early) and any guests or visitors. In a commercial setting, clear signage in restrooms can help (e.g. a sign politely reminding folks to bin sanitary products and wipes). For staff, have protocols for disposing of kitchen fats and chemicals properly. It might feel awkward to discuss, but many sewer backups are caused by well-meaning people who simply thought “this one little thing won’t hurt.” So, spread awareness. The good news is public awareness in the UK is improving, surveys show more people each year understand what not to flush. Campaigns like “Love Your Loo” and “Bin the Wipe” are making a difference. Be part of that positive change by setting a good example in your home.

Routine Maintenance and Checks

Even with perfect usage, any septic or treatment system needs periodic care. Desludge your septic/treatment tank on the recommended schedule. Regular pumping prevents the buildup of solids (including any non-flushables that snuck in) from reaching a level that could clog your system. During pump-outs, the service technician can also check for signs of abuse (like masses of wipes or lots of grease) which can be a wake-up call to improve habits. If you use a small treatment unit, adhere to the service schedule (often an annual service to check the aerator, pumps, and that the effluent quality is good). A healthy, well-maintained system is more forgiving if a small amount of something odd gets in, whereas a neglected system is primed for failure. Bonus tip: keep records of when you last emptied or serviced the system, and note any issues encountered, it helps in troubleshooting and reminds you when maintenance is due.

Follow Manufacturer/Provider Guidance

Manufacturers like GRAF UK provide user manuals and guidelines for their wastewater systems. These will include do’s and don’ts specific to your model. For example, GRAF UK’s literature explicitly lists prohibited substances (many of which we’ve covered) and even suggests precautions like using a grease separator for high-fat wastewaters. Make sure you’ve read these materials. If you inherited the system with a house and didn’t get the manual, check the company’s website or reach out to them or a local distributor, they often have PDFs or advice available. Following these guidelines not only keeps your system running smoothly but may also be necessary to meet warranty or regulatory conditions.

By implementing these best practices, “binning it” becomes second nature. You’ll significantly reduce the risk of blockages and failures, prolong the life of your wastewater system, and contribute to a cleaner environment.