Rainwater Harvesting

Climate changes impact weather, including patterns of rainfall, temperatures, and seasonal patterns. Drought can influence the viability of garden projects, and excessive rainfall will impact Fenland areas as rising sea levels prevent the usual ways to dispose of flood water.

I believe that all additional housing developments should feature rainwater storage to smooth the impact of sudden rainfall and provide a degree of sustainability when water is in short supply.

There is also the issue of using treated (potable) water for washing clothes, flushing toilets, cleaning outside, and watering plants. High-quality water must be used for drinking and personal hygiene, but using it for everything will become unsustainable and potentially expensive.

I linked three 800l tanks with a submersible pump that supplies rainwater to one WC, the washing machine, and an outside tap. I included a filtration system to clarify the water, but even after significant rainfall, the leaf trap in the guttering downpipe and moving from one tank to another significantly assists the clarity of the water.

In the event of a drought, when water drops below 20% of maximum capacity, the system reverts to mains water backup. When the tank level triggers the level sensor, the PCB board allows 45 minutes of mains water restricted to 4 litres per minute (180 litres) to enter the tank once the float switch reaches full position. This means anything plumbed in will continue working all the time.

I deliberately left one WC plumbed in to the mains water supply just in case something catastrophic occurred. All showers and hand washing use potable water. With two adults, our water consumption has reduced from 150 litres daily to 90. We also pay a lower standing charge and reduced sewerage (because sewage is proportional to water consumption when your property has a water meter). Suppose your property does not have a meter. In that case, charges are based on the rateable value according to Council Tax rate bands – if you are a low user of water – you should consider having a meter installed in my opinion.

During dry spells, I can still wash the car even if there is a hosepipe ban, I can water the garden, and the plants enjoy rainwater rather than processed water. The soft water used by our washing machine uses less detergent.

So we look forward to sunshine to power up the batteries via solar, and when it rains, we gain free water. Best of all, the sun sometimes shines all day, and the rain falls at night.