Rain Water Plumbing and Rain Harvesting

Rainwater in environmentally friendly and can help your garden and plants grow. Plants respond best to the natural rainwater rather than from what comes from the faucet or tap, which can be contaminated with impurities. Rain water is natural and, more importantly, it is free. Gathering rain water will also reduce the wear and tear on a septic tank. The simple way to gather rain is to collect it from your own rooftop.

Very little plumbing know-how is required as the down pipe can simply be removed and the water from the roof can then be diverted into a container of your choice. There is no need to buy an expensive water butt with attachments because it is much cheaper to do the job yourself. I tried the various marketed butts previously and they were always too small to be practical. The filled too quickly and they did not provide enough water to water the large plot of vegetables properly. The butts or rainwater barrels that are available commercially are very small and you will find plenty of 20, 30 and 50 gallon tanks for sale everywhere. Forget about them is my advice, and install a 300 gallon water tank instead. You will not need to worry about limescale either as rainwater is a soft water and will not cause scaling on your tank.

A 300 gallon water tank will fill overnight in average rainfall conditions. In constant heavy rain my water tank has filled in 3 hours. It does depend upon a number of factors, the main one being how much roof area you have available to you for catching the rainwater. The tank should be fed from the down pipe of the biggest roof area or gutter run, but it does depend on how big your house is as well as how much rainfall you get where you live.

Remove the down pipe from your gutter (on a dry day). Place the empty tank as near as possible to the rainwater down pipe. Redirect the water to the opening on the storage tank. See the simple rainwater diverter I used in the image opposite. The water butts easy to move about when empty. Avoid plumbing problems later on by allowing 4 inches of clearance between the tank and the house wall. The reason is that the tank will expand when full of water (also when it freezes during the winter).

Raised tank

As the water butt will have the outlet valve very close to the bottom of the tank it is sometimes a good idea to build a plinth for the tank so that when it is in place (and full) you will be able to fill water directly into watering cans and buckets more easily.

Weight consideration

The plinth or platform will need to be very strong as 300 gallons of water is quite heavy, The easiest option is to place the tank on the ground as it will gravity feed with the weight of water when full. This is the least expensive option. If you wish go more professional you could consider building a permanent ferrocement water tank.

Apart from the environmental advantage there can be a financial one too. In my own case, water is fed into my home from a well and this has an electric pump. In the days before I gathered rainwater I used ordinary hard tap water from the faucet. So, for every watering can or bucket of water drawn a certain amount of electricity was used.

Free water

When watering a large vegetable area, new plants or a growing tunnel this became a significant amount of money. These costs are avoided when you use free rainwater. The initial outlay for the tank and the on-off valve are the only charges incurred. You might modify the system later on with a rainwater grill to catch leaves and other debris.