All stormwater systems need to be maintained to continue operating effectively, and rainwater harvesting (RWH) is no exception. Unfortunately, many owners do not care that their stormwater BMP is not functioning due to lack of maintenance. Maintenance of RWS systems is critical for owners that depend on their continued operation and associated utility savings. Proper maintenance of a RWH cistern helps protect water quality and ensure system performance.
1. First Year Observations = Successful Start-up
During the first year, quarterly inspections of the cistern are recommended to assess site loading and verify initial operation. After that, annual inspections should be sufficient.
2. Preventative Maintenance = Long Term Savings
Check the calming inlet, outlet, and cistern overflow for blockages and the amount of accumulated sediment annually or at a more frequent basis depending on the observations during the first year in operation. A drainage area of one acre will generate almost 1 million gallons of runoff annually (in areas with 36 inches of rainfall). Over time the runoff will carry a significant sediment load despite pretreatment, and eventually accumulated sediment should be removed.
3. Easy Maintenance Access = Long Life
Maintenance cycles are 5 to 10 years or longer in most cases. It is important for engineers to design access points for cleaning, inspection, and repair to ensure the owners benefit from the RWH system for the full life of the system. Closed systems that do not provide access to enter the cistern can severely limit the ability to do maintenance or repairs and a small installation error or internal blockage can be extremely costly or render the system obsolete. Open and accessible systems ensure successful operation of the cistern for the full design life.
This is an excerpt from the Professional Development Article: Cistern Design Considerations for Large Rainwater Harvesting Systems. Read the article and take the quiz online for free PDH credits.