SITE PREPARATION


Stop costs running away


Collecting rainwater for domestic use is nothing new; it’s been done since Roman times and is still used today in modern, sustainable homes. Jae Lester from RainWater aresting looks at how technology has changed, though the principle remains unchanged


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n the UK we have the problem of either too little or too much water. Obviously preventing 30% leakage of the mains supply will help enormously but there are other things that can be done to support this. Sometimes we need to look to the past to find solutions for the future.


WHAT IS A RAINWATER HARVESTING SYSTEM? Water is collected off the house roof via standard guttering and downpipes. It is filtered and stored in an underground tank. When required it is then pumped back into the home to be used for ushing toilets, washing machines and outside use which greatly reduces the demand for mains supply. The question in our quest for sustainability is should we use mains water for non-drinking purposes There is no need to ush toilets with processed drinking quality water bought from miles away. Installing a system is best suited to a new build or major renovation as there will be a rainwater feed to toilets and other non-potable appliances. Indoor taps, basins, showers and baths will remain on the main supply. The harvesting tank is buried


underground – there is no light and only a small temperature variance to keep the water cool and fresh. Tank size calculators are available on the web. Sizes are calculated on location, collectable roof area, number


nov/dec 2022


Returning water to the storm drain at a controlled rate is an efficient way to collect for reprocessing which may become more important


with increased demand


of peopletoilets, and application for the water. Systems are designed to require minimum maintenance. There is a filter which allows water to ow into the tank but leaves and debris are directed into a soak away. Filters are designed for easy access so once or twice a year it is worth remoing and ushing with clean water. Within the tank, there is a pump


which activates when a drop in pressure is identified.


WHAT HAPPENS IF THE RAINWATER IN THE HARVESTING TANK BECOMES LOW? Tank sizes are calculated traditionally on a  day supply, as it was assumed that it would rain within that timescale. However should the water run low we still reuire the toilets to ush. Therefore if the water is going to be used within the home and not just for the garden it is important to specify a mains back up system. There are two main types. In a direct feed system the pump is directly connected to the appliance and runs eery time a toilet is ushed. f rainwater becomes critically low a small amount of mains water would be introduced into the underground tank.


In a gravity system the water is pumped up into a header tank and appliances are serviced from there. The latter method only requires the pump to be operated when the header tank needs replenishing. Running costs can be as low as 1p per person per day. Systems are designed to prevent any cross contamination and it is important to consider WRAS (Water Regulation Advisory Service) approved systems. These have undergone extensive testing and are accepted by all water providers as compliant if installed in accordance


www.sbhonline.co.uk 33


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