CONTENT SUPPLIED BY RAINWATER HARVESTING
This was a recent statement by Ofwat. A call for urgent action adding ‘Planning for a resilient and affordable water supply is not yet effective’ The average person uses about 140 litres a day, but Government experts believe that this needs to fall to 100 litres. Interestingly the amount of rain falling per annum hasn’t changed significantly but what has changed is longer drier periods and then heavier showers plus the number of people requiring supply.
The document did not explain how to cut water usage. Low flush toilets are not always effective. So is there a viable solution to supply?
Rainwater harvested off the roof can be used for toilets, washing machines and any outside use. This can be a significant saving to mains supply. It makes no sense to flush toilets with high quality drinking water bought from miles away.
RainWater Harvesting Ltd design and manufacture rainwater and mains back up systems in the UK for UK homes.
Rainwater is collected via standard gutters and downpipes, filtered then stored in an underground tank. Tank sizes vary but usually between 3000 and 7500 litres depending on usage. Capacity is based on BS8515 which includes available roof collection area, usage and average rainfall. There is a tank size calculator on our website.
Water is then pumped back into the home. There are two types of systems.
Back Up In a Box-Direct Feed
Every time the toilet flushes the pump runs to refill the cistern. Should rainwater become critically low a measured amount of mains water is introduced into the harvesting tank. This is switched automatically and reverts to rainwater after the next rainfall.
Rain Director-Gravity Fed System
Rainwater is pumped from the harvesting tank into a header tank and appliances are serviced from there. The pump only needs to run once or twice a day and therefore an efficient use of electricity. The Rain Director costs about 1p/person/day to run. Should rainwater become low mains water is fed into the header tank and so again a very efficient method. It will revert to rainwater supply automatically.
Installing a rainwater harvesting system can support a planning application on water usage. As importantly it can also help with drainage issues and acts as a Sustainable Drainage System (SuDS). During heavy storms fast flowing excess water is collected off the roof into the harvesting tank. This extra capacity can then be released at a calculated low discharge rate. This can be as low as 0.03 litres/second so will not overwhelm the drainage system.
The systems are designed to be low maintenance. The underground filter should be checked once or twice a year.
Complete systems cost between £1500 and £3000 ex VAT. The systems are designed to be installer friendly and requires a small input from the grounds worker, electrician and plumber.
In the UK we are privileged to have a high quality water supply. By installing a rainwater harvesting system for non-potable applications we will be safe guarding our future mains water supply without having to ‘change’ too much.
