W
ith many areas struggling under drought conditions and municipalities restricting access to water for certain activities, it makes sense to collect the rain that falls on the roof and repurpose that water for garden watering or other non-potable uses.
Including a basic rainwater collection system in a new home is simpler than ever. The trick is to develop ways to channel rainwater from the roof surfaces into gutters and downspouts that pipe into a water collection cistern for later use.
First take a look at your roof area and determine where the water will tend to collect and flow. You’ll want to connect the flow from major areas on the roof to 2-3 primary collecting downspouts. Using modern gutters and downspout designs that keep leaf debris and other large particulates out of the gutters will ensure easy flow.
The next step is essential in water collection. Instead of leaving the bottom end of the downspouts open, connect each downspout to flexible tubing that drains into a common collection tank or cistern. You’ll want to make sure that each downspout outlet is connected via a downward sloping tube to the collection tank. The system can be designed and installed at the same time as the septic or foundation work so that the tubing and collection tank can be buried out of site. Any natural sloping or hill features should be utilized to maintain a steady downward flow of water and avoid back-ups.
Estimating tank size
There are several factors that should be considered in sizing the rainwater collection tank. The square footage of your roof is the first calculation. This will determine the area where rainfall will be redirected. Average rainfall is the next calculation to include. Access your local meteorological station for the average rainfall for your area, using at least 5 years of records. Third, estimate the amount of water you’ll be using for gardening, watering lawns, washing cars or other non-drinking uses. A useful calculator on the Rain Harvesting website can provide tips on calculating the size of your holding tank.
Types of Collection Tanks
Collection tanks are available in a number of configurations: concrete, metal, steel, plastic, fiberglass or bladder type storages. These tanks can be installed either aboveground or underground depending on the configuration. The storage bladders work well in areas where space is limited and can be tucked under decks or porches.
Accessing Stored Rainwater
Once the rainwater has been collected, there are a couple ways to access it. Many homeowners opt for a simple electric pump, similar to a submersible well pump. One practical way to access water is a suction-based shallow well hand pump (see right) made by Bison Pumps in Houlton, Maine. The pumps work particularly well for garden watering as the spout has a thread to fit a standard garden hose. The pump action is easy and can get water up and out to garden or lawn areas with just a little effort.
Once the rainwater collection system is in place you can feel confident in having water from a second source, so long as the rains gods provide!