"I have city water. Why should I catch rain?"

 Good question! After all, city water isn't that  bad, right? Well, okay, some city water is horrible, but let's say your city/county water is reasonably clean. Why bother with rainwater?

Because the water you depend on may not be dependable. Why? Because municipal water systems operate with electricity and pump water to you under pressure - no electricity, no pressure, no water. So if your electricity is interrupted, you lose lights and water.

"Oh, but that happens so rarely." Exactly! The point is that it does happen and can happen with no warning. How long can you live without water? Right again, not very long. What would you do if your water supply was cut for a week? For a month? It could happen.

So why risk the safety of yourself and your family, by being totally dependent on a water supply that could shut down tomorrow, or today? You can secure your own water supply easily by installing - or having someone install - a simple rainwater harvesting system that will give you clean water all year, for free!

"Can I use my roof?" Many people do, but water quality depends on what kind of roof you have and what you intend to use the water for. If you want drinking-quality water, good catchment surfaces include concrete, clay tiles, slate, sheet steel with baked on enamel, polycarbonate and fiberglass.

Galvanized metal and asphalt shingle roofs will produce water that may be suitable for washing but not for drinking. These roofs contaminate rainwater with zinc and petroleum chemicals respectively. However, solutions exist.

"Where do I start?" Right here, by first answering a few basic questions:

Will this be a backup or a primary water supply?
A backup system is your Plan B, your emergency water supply for those times when your main or primary system stops working. It is designed to provide as much or as little water as you think appropriate, until your primary supply is operating.

A backup system can be scaled to provide only emergency water - drinking, some washing, bathing - or it can be a parallel primary system, with as much water as you normally use. In this case, it can become your primary water supply (since the water is free) and your city water can be the backup! Your choice.

How much water do you need this sytem to supply?
Many people have little idea how much water they use each day - it just goes down the drain and toilet, unaccounted for. A few years ago, the average US home flushed about 40% of its drinking-quality water down the toilet, just to get their waste out of sight. Some of us like to take long, wasteful showers, or soak in a bathtub with many gallons of water. Calculations

You will have to keep track of your water use for a week or so. Count the gallons you use for a week and multiply by 52. That's what you need for a year. Correction: That's what you USE in a year. You probably need much less. See Calculations.

What will the water be used for?
A safe amount to calculate for drinking water is a gallon per person per day, or 365 gallons per year. A relatively small system can supply this amount. However, drinking-quality water requires that all materials that come in contact with the water are relatively inert - they don't contaminate the water with chemicals.

In order to supply a home with water for everything, it is possible to install two systems: one for washing and household use, another only for drinking. This way, the strict requirements for drinking water need not apply to the larger system.

Do you have space for a storage tank? Need a permit?
Water storage tanks tend to be large - about 6' to 8' in diameter and from 4' to 10' high or more. Things that large tend to attract attention, especially when they arrive in your neighborhood.

Check with your local officials to be sure that you can have the tank in your yard. You don't want to find out later that you can't.

Do you have a budget for this system? How much?
The storage tank will be the most expensive part of the system, unless you are installing a new roof. Polyethylene tanks cost between $0.50 and $1.00 per gallon capacity new.

Will you install your system or will you have it installed?
If you hire someone to install your system, locate an experienced person, and expect to pay $25-$40 per hour. Skilled labor (example: auto mechanic - $65 per hour) is money well-spent, IF you get what you pay for.

If you are handy with tools and understand how a rainwater system functions, you may be able to install your own, saving you money. However, be realistic about your skills - this is your home's water supply, not a drip irrigation for your tomatoes.

Will you use an existing roof or surface, or will you build one?
Ah, the tough question. Well, many people have asphalt shingle roofs, because they're cheap. Asphalt is a petroleum product and smells like, well, oil. So does the rainwater coming off the roof - it's contaminated with asphalt and unsuable for drinking.

You can use that water for washing, but personally, I don't like to brush my teeth with it. Try it and see what you think. Putting on a new roof may be out of your budget, so what can you do?

Look at the photo at the top of this page. I installed this system to collect water only from the fiberglass patio roof, because the house has an asphalt shingle roof. I even put aluminum flashing in two house-roof gutters to block any water from going over to the patio roof catchment.

If you don't have a suitable catchment for drinking quality water, you have several options. You can create another roof or catchment surface. You can resurface part or all of your existing roof (expensive). You can create a surface catchment system - collecting rainwater at ground level.

Climate change may force all of us to consider a backup water system. Global warming, and the resulting disturbances to weather patters, will impact the availability of water, even in places where water is now plentiful. More on this here.