It happens more frequently than you would think—a “normal” water shortage turns into a full-on drought. Now you’re stuck without enough water to take care of your landscape and preserve your plants. If you do water your plants, you do so illegally. That’s dangerous, self-serving, and (on a more practical note) sets you up to pay dearly in fines. But what if you planned ahead. Rainwater capture lets you store it up for those times when water restrictions prevent normal irrigation. A little bit of planning now (especially by builders looking to differentiate themselves in the market) can help homeowners save money and keep their lawns alive.
Harvesting Rainwater for Irrigation
It’s no big mystery that homeowners with extensive or water-intensive landscapes require a lot more water than the average homeowner. Also take into consideration that, in the average residential irrigated neighborhood, up to 40% of the normal water consumed goes to outdoor use. That is a lot of water to just take care of your plants and landscaping. Much of that also gets wasted due to evaporation and other concerns.
Hey, it’s there, why not use it? You can harvest rain for indoor plumbing use (think flushing toilets and laundry). However, its main use typically falls under supplementing irrigation. You can also use it for watering gardens or even washing the house or car. Other uses include anything not involving regulations or costly purification of the rainwater.
So how do you do it?
Methods for Rainwater Capture
Well, there are three forms of rainwater collection:
- Rainfall (rain) barrels
- Above-ground cisterns
- Buried (hidden) tanks
Let’s say you finally decide to use one of these rainwater capture (catchment) systems. First, consider how much water you need to collect. As a general rule of thumb, you can collect 600 gallons for every inch of rain that falls on a 1000 square-foot surface. That approximates an average-sized roof.
So how do we figure out what you need? Well, plants need about one inch of rainwater each week (or 0.5 gallons of water for every square foot). That means you need a 55-gallon drum (or similar) to cover 100 square feet.
What About Purifying Collected Rainwater for Drinking?
Got larger needs, or want to purify collected rainwater for drinking? Aside from the specific issues associated with the requirements of your local municipality, the main collection source will be your roof. Never use a parking lot or ground location due to chemicals. You also want to invest in some additional rainwater capture and storage components. These may include:
- Cistern – these larger storage tanks retain water and let larger particulates settle to the bottom of the tank. While most cisterns are underground metal, fiberglass, or plastic containers, some can be above-ground in areas where it is difficult to dig down low.
- Cistern Overflow – this pipe ensures that an overabundance of rain doesn’t create a problem. It moves water from the cistern to the storm drainage system in the event of an overflow. This is, as you can imagine, a crucial component of any water collection system.
- Pump – if you are irrigating, this is the device that will provide enough pressure at the point furthest from the water source, so that a lawn can be watered for example.
- Disinfection system – there are lots of options for this, but to have a potable (drinkable) water system, you need a disinfectant or water purification system.
So How Does Rainwater Capture Work?
In principle, a rainwater capture system works simply. Once rain falls, it rolls off the roof and is gathered into the rain barrel or cistern. At that point, it is screened and filtered to remove larger debris and sediment. The pump moves the water from the tank (when necessary). The overflow system sends excess rainwater to the storm drainage system to avoid flooding or other problems. You should always keep rain barrels and cisterns out of direct sunlight. This reduces the growth of algae (think of a swimming pool).
Why Capture Rainwater for Irrigation?
There are a bunch of reasons to do a rainwater collection (“catchment”) system. First off, it’s “green”. That often seems like a code word for “expensive and inefficient”. In this case, however, a simple rainwater collection system can actually make a lot of sense. This holds especially true when used for gardening or irrigation. Builders can really grab hold of these ideas because it lets them offer an efficient solution to clients that can save them money over time.
Since the materials aren’t all that expensive, putting in some up-front labor can really produce a home that is valued more and can sell more quickly. After all, it’s an easy sell to tell your customers that they will have the lowest drinking water bills in the neighborhood and can water their lawns more frequently.
And yes, it is nice to the environment…