Water

Page is always being updated, check back for more Installing a Rain Water Collection System

This page is still under construction, and may be incomplete.

The essentials of a rainwater collection system are 1) a collecting surface, 2) gutters and downspouts, 3) a container to hold the water, and 4) some kind of filtering to keep roof debris and insects (primarily mosquitos) out of your containers.

It is possible to build a collecting surface if you don't have access to a handy roof. In the days of sailing ships, it was common to rig a large sail to catch rainwater and funnel it into the ship's water storage barrels. I read of a collecting surface in New York City that was a series of shallow wooden trays emptying into a barrel, and I saw an installation in a major city that consisted of large concrete half-rounds placed end to end in the narrow space between two buildings. The run-off from those was collected in a large pond at ground level behind the buildings. Ingenious people will certainly come up with other ideas when the need is urgent. But the roof of your house is ideal. If you can't use that, any kind of outbuilding or even just a small storage shed will work, though it will provide less water.

Much has been written about what kind of roof is appropriate. If you don't plan to ever drink the water, your only major concern is whether the roof has been treated with a poison to kill moss. You don't want to put that water on your vegetable garden. A flat bitumen (tar) roof may be unacceptable as well, for the same reason. But most homes and residential outbuildings have roofs that are just fine for collecting rainwater. A standing-seam metal roof is clearly the best, especially if you anticipate ever having to use the water for drinking, but don't let the lack of that keep you from saving rainwater at all.

If you don't have gutters and downspouts, they can be installed by a reasonably handy person. Most large building centers carry both aluminum and plastic components, and there are numerous sites on the internet that detail how to put a system together. It's difficult for me to climb ladders because of a knee injury, so I had no choice but to pay a professional installer. If you do this, get as many estimates as possible. Several of the contractors I called didn't want to install gutters on a mobile home at all. The range of estimates I did get varied by nearly 100 percent. In the end, I went with the cheapest price, not just because it was the cheapest, but also because I felt comfortable with the owner of the business after my conversation with him. And after watching the installation, I'm confident I can put gutters on the outbuildings myself.

Some of kind of leaf guard or downspout strainer is also a good idea. Amerimex makes a snap-in strainer for 3" guttering that works very well here, and is available at most of the large home improvement stores. The home is surrounded by large pine trees, and before I put the strainers on, the gutters were completely clogged with pine needles. You can buy these strainers by the box (of 25 pieces) or individually. It took two boxes and one or two extras to cover the gutters on this 70' mobile home. If you don't have as much of a debris burden as I do, a simple downspout strainer, pushed into the top of each downspout, might be sufficient.

Containers can be anything from plastic trashcans to food-safe barrels meant especially for water storage to salvaged barrels, food-safe or otherwise. See the page on acquiring and storing water for more detailed information on different kinds of water containers. I have two varieties: barrels that once contained car-wash detergents, and food-safe barrels in which olives were shipped from Italy.

It isn't essential to filter the water if you don't plan to use it for anything but irrigation, and if you can seal the opening so mosquitos can't get in. If you're only going to use the water for your plants, you may not care about pollen, bird poop and dead bugs. But if you do want to filter the water, I recommend the directions at the WikiHow site, How to Build a Rainwater Collection System. The author chose not to use any kind of diverter or first-flush device, but except for that, his instructions are extremely well written and well illustrated. There is also a video, if you prefer that format (scroll down to the bottom).

Putting the system together

You'll need some way to cut your downspouts at an appropriate point to empty into your barrels (or trashcans or whatever you use). A hacksaw works best for aluminum downspouts. 2 x 3 plastic downspouts can be cut with a utility knife. I have aluminum guttering and downspouts, so that's what the pictures will show.

You'll need to decide whether to include a seasonal diverter (to keep your barrels from filling during winter rainfalls). These come in multiple styles, but the one I chose for this barrel is shaped like a Y. Some ingenious person turned this standard fitting upside down (its original use was to connect two downspouts together), and added a lever that controls a small trough inside. Turn the lever one way and the water runs into your barrel. Turn it the other way and it drains down through your original downspout.

This type of fitting does have one disadvantage. You'll have to move the bottom portion of the downspout (the part that you cut off) over about two inches. If there is no wall stud at the new location, you'll have to come up with some other way to secure the strap. I used a 2' x 4' piece of 1/2" exterior plywood as a backboard, since the new location would have put the mounting screw through nothing but thin aluminum siding. This piece of wood also allowed me to more easily mount the first-flush diverter (which can be heavy when it's filled with water).

I used a good-quality exterior oil paint to paint the plywood, since it will be exposed to the weather. I painted both sides to prevent warping, and paid good attention to the edges, filling them with wood filler first, and then giving them several coats of paint.

The plywood was then mounted to the wall with 1-1/2" screws through the studs.

The single leg of the wye adapter needs to be crimped so it will slide into the cut end of the downspout. This picture shows the open ends of the double legs. You can see that each corner is folded in to make the overall size just a bit smaller. Because this adapter was originally intended to connect two downspouts to a single downspout, these ends would have fit up inside the original two downspouts. We're using this upside down from its original purpose, so the single leg must be crimped to fit inside the bottom end of our downspout.

To do this, grasp each corner with a pair of needle-nose pliers and twist the metal until it turns inward. You won't get as nice a crimp as the machine-made one on the other ends, but it will work.

Now push the single leg of the wye up inside the downspout coming from the gutter, and push the cut off piece of downspout up around one leg of the wye. You're adding roughly 10" to the length of the original downspout, so if you need to trim it a little shorter, this is the time to do it.

The next step is to attach the whole business to the plywood backboard. I had already removed the original strap that held the downspout in place, and put a dollop of silicone sealant in the hole to keep it from leaking. I replaced the strap around the point where the wye connects to the new downspout location. This was partly to conceal the cut ends, but also to strengthen the point where two pieces meet.

Now that the adapter is in place, the first-flush fitting is installed. The end of the wye just sits down inside the fitting, which is essentially a thin-wall pvc tee. It would have been nice to be able to seal this connection, but I haven't had a problem with anything getting into it and clogging it up at that point.

This tee is made in Australia, and intended for use with 90mm pipe. Fortunately for us in the US, the inside diameter of 90mm pipe is close enough to the outside diameter of schedule 40 pipe that you can get a good compression fit. The installation instructions suggest using 3 feet of 3" pvc. I chose to use only 2 feet, partly because of the weight and partly because I could buy a 2 foot section already cut.

The tee comes with a fire plug and screen that must be glued to the bottom of the pvc. After securing the plug and its drain to the bottom of the pipe, drop the plastic ball inside the pipe. Now cement the top of the pipe up inside the body of the diverter. Use PVC cement from the hardware store for this purpose. Directions for using it are on the container.

The tee is now secured to the backboard with the mounting straps that came with it. In use, the water runs straight down into the 2 feet of pvc until the ball, floating on top, comes up into the bottom of the tee and seals the opening. Then the water runs out the port on the side into the barrel.

Thin wall pvc fittings give a good compression fit inside the tee, so I mounted a 45 degree elbow there and ran a section of thin-wall drain pipe down to the top of the barrel. Another 45 degree ell puts the water right at the opening of the filter mounted on top of the barrel. (Notice that the hole in my filter is round, rather than the 2x3 rectangular hole demonstrated in the filter instructions.)

The barrel itself sits on two tiers of concrete retaining wall blocks, with 2 4 x 8 concrete blocks in the middle to provide additional support. The empty space around the middle blocks is filled with gravel. The barrel has a garden hose bibb screwed in to the bottom for easy access to the water. To prevent stress on the barrel from connecting and disconnecting a hose, I made up a 3-foot length of hose that stays connected to the barrel. It has a male fitting on the other end, so a regular garden hose can be connected to it. In practice, the three barrels on the back of the home are connected to a manifold at one corner. The single outlet from the manifold goes to the garden's drip irrigation system through a timer that turns on the flow once a day in the early morning. For most of the summer, we have enough rain that the barrels stay full and gravity is sufficient to get water to the garden. In fact, I plan to add another barrel at each downspout, since the first one fills so fast when it rains.

Can this water be used for drinking water? Yes and no. You certainly wouldn't want to drink it straight out of the barrel. A paint strainer doesn't provide sufficient filtering to remove biological pathogens like bacteria, viruses or cysts. After filtering through a homemade "berkey" filter, the water tested negative for coliform bacteria. That doesn't mean it didn't have other contaminants. Right now we're not drinking it, since we have a good well. In an emergency, that might change. I would still want to expose it to sunlight (SODIS--Solar Water Disinfection) to kill viruses. A reverse osmosis filter would remove most chemical contaminants. At some point, in an emergency, you have to make a decision between drinking water whose purity you can't be certain of, and becoming dehydrated. With additional filtering, this rainwater would be better than the water from many other sources. It could certainly be used for laundry. In the meantime, it keeps the garden and fruit trees nicely irrigated.