How to Maintain a Rainwater Harvesting System?

Posted by Callum Vallance-Poole, on April 12, 2021.

rainwater harvesting system

All things in life require some form of maintenance to keep them in good condition. This is true of equipment, relationships, vehicles, houses, and of course, rainwater harvesting systems. The good news is that maintenance of a rainwater harvesting system is simple and can often be done quickly and with little cost. There are several companies now who offer maintenance contracts and service agreements, and these are often a good route for homeowners to choose because these companies should know what they’re doing. They should have all of the equipment to do the maintenance and if the contract is any good, then it should include a full tank clean-out at some point within the contract term. Of course, there are bound to be some which are not as good as others so choose wisely and check what is carried out on maintenance visits.

The British Standard Code of Practise document provides a suggested maintenance schedule to help owners and users of rainwater harvesting systems to keep them well maintained.

Here is what they suggest.

Extract from BS 8515:2009 (British Standard for Rainwater Harvesting) …

7 Maintenance

Human entry into tanks should be avoided, wherever possible. Where entry is essential, it should only be undertaken by trained personnel with personal protection equipment suitable for confined spaces.

Maintenance procedures should be in accordance with the manufacturer’s maintenance recommendations.

In the absence of any manufacturer’s recommendations, the maintenance schedule given in Table 5 should be followed. The maintenance intervals listed here are for initial guidance, but the frequency should be modified in the light of operational experience.

A log should be kept of inspections and maintenance.

System ComponentOperationNotesFrequency
Check that there are no leaks or blockages due to buildup of debris; clean the gutters if necessaryAnnually
Check the condition of the filter and clean, if necessaryAnnually
Storage tank/CisternInspection/
Check that there are no leaks, that there has been no buildup of debris and that the tank is stable and the cover correctly fitted Drain down tank and clean the tankAnnually
Every 10 Years
Pumps and
pump control
Check that there are no leaks and that there has been no corrosion; carry out a test run; check the gas charge within the expansion vessel or shock arrestorsAnnually
water supply
InspectionCheck that the back-up supply is functioning correctly, that there are no leaks and that the air gaps are maintainedAnnually
Control unitInspection/
Check that the unit is operating appropriately, including the alarm function where applicableAnnually
Water level gaugeInspectionCheck that the gauge indication responds correctly to the water level in the tankAnnually
WiringInspectionVisually check that the wiring is electrically safeAnnually
PipeworkInspectionCheck that there and no leaks, that the pipes are watertight and that overflows are clearAnnually
MarkingsInspectionCheck that warning notices and pipework identification are correct and in placeAnnually
Support and
Adjust and tighten, where applicableAnnually
UV lampsInspection/
Clean and replace, if necessaryAnnually

Obviously not all systems will include all of the items listed in this table and so some of the above will not be required on some systems. As it says also, the frequency of the checks should vary in accordance with each individual situation dependent on operational experience. For example, a system which is installed on a property which is directly under a row of trees which drop leaves on the roof and fill the gutters, may need more frequent gutter and filter inspection than on a property with no over-hanging trees at all. Each situation is different, and this should be considered.

Our tips for maintenance are to check the following things annually as a minimum.

  1. Check the guttering on the property is clean & clear.
  2. Clean the filter unit in the tank (or the pre-tank filter, whichever you have).
  3. Ensure the pump is operating correctly as it should be by testing it a number of times.
  4. Ensure the mains water top-up or backup system is working as it should be by testing it a number of times, moving the float-switch and simulating the absence of rainwater to make sure mains water is provided in its place.
  5. Check the cleanliness of the water provided and make sure you’re happy with it.
  6. Check pipework connections and fittings to make sure all are tightly connected with no leaks.

We recommend that underground tanks are cleaned out regularly, with no longer than 5 years between each clean out. This is a shorter time frame than that stated in the British Standard as you will see but we believe the water quality and cleanliness should be no different when using a rainwater harvesting system to when using only mains water. To keep it clean and clear, the tank must be kept cleaned-out. It is not expensive to have the tank cleaned-out every few years and the cleaner the water going through the system, the longer all of the parts will last. When small particles of dirt and debris flow through the pump and the pipework and the valves, it all builds up and will have a detrimental effect on the overall system. The cleaner the water the better, so keep up good maintenance practise!

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Marketing Coordinator - Based at our UK HQ in Banbury, Oxfordshire, Callum is responsible for promoting Water Management Systems, Attenuation Tanks, Treatment Plants, Rainwater Harvesting Systems and more!