phprainwater - how much rainwater can I collect?

HOW MUCH CAN I COLLECT?

That’s reasonably easy too. It is simply a calculation of the building footprint area times the amount of rain, with an allowance for losses.

For example a building measuring 10m x 25m will cover an area of 250 m2.
If you have 25mm of rainfall, that will be a total rainwater volume of 6250 litres. That’s enough for WCs and laundry for 4 people for 3 weeks.

That’s reasonably simple. You can collect rain from 2 sources

1. Drives, paths and patios. OK for gardens, but not an ideal source if you are intending to use the water in the house. There is a risk of contamination from oil, dirt and animal waste. Plus it’s not always very easy to collect

2. Roofwater is usually directed through down pipes and

stormwater drains and is therefore easy to collect. There is also much less risk of contamination.

Rainwater will normally be stored in an underground reservoir, the size of which will be calculated according to the size of the collection area

Rainfall varies greatly over the country. Wales, Scotland and the West Country have 2-3 times as much as East Anglia. However, even in low rainfall areas, the amount of collectable water can be very substantial, especially if you install a large enough tank. The chart at left shows typical average rainfall in different parts of the country.

PHP Rainwater Systems are particularly suited to new buildings, where it is much easier to incorporate the system into the design of the house. It is easy to install the reservoir when the groundworks and drainage pipe work is being installed.