How to Harvest Rainwater

 How to Harvest Rainwater

Harvesting rainwater is not only an effective means of saving water, but is also effective in saving money too.

Mains water is precious but it is highly likely that a point in time will come where the mains water supply will no longer be able to meet the needs of our growing population. As more water is demanded, the price we pay will increase.

What better way of dealing with this than to make use of the water that falls freely from the sky. And, it doesn’t have to be expensive to get up and running. There are solutions to fit all budgets and available space.

Rainwater Vs Greywater

While both rainwater and greywater are effective ways of reusing water, they are not the same!

As you know, Rainwater is fresh precipitation that falls straight from the sky. It is completely free of salts, chemicals, pharmaceuticals, and minerals; it’s pure!

Greywater on the other hand, is water that has already been used in a home and has been discharged from washing machines, showers, tubs, and bathroom sinks. Kitchen sinks don’t make the list as that water is known as ‘blackwater’ due to the bacterial load, so in sum, you can think of greywater as “everything but the kitchen sink” (and of course the toilet).

Because rainwater is relatively clean, it can be stored safely for long periods of time and released only as needed. As the rainwater heads into the container, particulates are filtered out, so the water doesn’t contain anything that might lead to growth or clogs.

Greywater is not recommended for storage and is best distributed directly onto the landscape.

Rainwater Harvesting Options

As I mentioned earlier, there are methods and systems to fit all budgets and available space. So let’s take a look at some of your options:

Rain Barrels

Rain barrels are the most common means of harvesting rainwater and involves placing a barrel in a position in which it can collect rainwater from a gutter downspout.

These take up minimal space but the capacity is generally only 50 to 100 gallons so it can easily overflow leading to a lot of waste.

Dry System

This method is much like a rain barrel but on a larger scale. Essentially, the collection pipe “drys” after each rain event since it empties directly into the top of the tank.

Maintenance of this kind of system is fairly easy but the storage tank must be located next to your house.

Wet System

This method involves locating the collection pipes underground in order to connect multiple downspouts from different gutters. The rainwater will fill the underground piping and the water will rise in the vertical pipes until it spills into the tank. The downspouts and underground collection piping must have water-tight connections. The elevation of the tank inlet must be below the lowest gutter on the house.

Unlike a dry system, the tank can be positioned away from the house but is more expensive to implement.

How to Harvest Rainwater

There are essentially three elements to a rainwater harvester.

  1. Collection area
  2. Transportation system
  3. Storage facility

Collection Area

The collection area is anywhere that the  falling rain doesn’t soak in to the ground and where the runoff can be collected. A typical example would be a roof.

The rule of thumb is that the average 25 foot by 40 foot home roof sheds about 600 gallons of water in an hour of moderate rainfall, around 1 inch.

If you have two downspouts leading from the roof, they’ll each divert about 300 gallons of water toward the barrel located under them. The more barrels you have, the more of this water that you can collect.

Transportation System

The transportation system is the gutters and downspouts along the edges of your roof. The material of these are not as important as the size as they have to be large enough to carry the water running off the roof.

You are going to need some kind of filters that will keep leaves and other debris from clogging the downspouts. If mosquitos are an issue in your location, you will need a fine mesh to keep them away from the standing water in the barrel.

Storage Facility

We have already looked at your options in terms of storing the collected rainwater but here we are just going to focus on using barrels.

Once you have chosen the location for the barrels, you need to dig out a 4-inch-deep area the length and width of the cinder block base. Fill the area with 1/4-inch pea gravel. This makes a base to help you level the cinder blocks and drain away water to keep your foundation dry.

The more water you can store, the better. Short lengths of hose can be used to attach individual barrels in order to link them together and boost the capacity of your system. And they can be added over time as you see how much water your garden needs.

Make a Simple Rainwater System

Follow the steps below to create your own system for collecting rainwater.

You will need the following:

  • 1 clean barrel
  • 1 S-shaped aluminum downspout elbow
  • 4 concrete blocks
  • 1 piece of aluminum window screen
  • 1 standard 1-inch hose spigot with ¾-in. pipe threads
  • 1 ¾-in. x ¾-in. coupling
  • 1 ¾-in. x ¾-in. bushing
  • 1 ¾-in. pipe thread with a 1-in. hose adapter
  • 1 ¾-in. lock nut
  • 4 metal washers
  • 1 roll Teflon thread tape
  • Silicon caulk
  • Hacksaw
  • Screwdriver
  • Pop rivet gun with rivets
  • Drill
  • Ruler
  • Spade
  • Level
  • Adjustable open end wrench

You need to start off by cleaning your barrel. Even if the barrel is brand new it is important that you scrub the inside of your container thoroughly with soap and water.

Use a spade to level the area for your barrel, set the concrete blocks in place and ensure that they are completely level. Place the barrel onto the blocks and hold the downspout elbow just above the top of the barrel and use a pencil to mark where the elbow will join the downspout — about an inch or so above the barrel is best.

Measure down 2 inches from the mark in the downspout. This will allow the downspout to fit into the elbow with a good, solid connection. Cut the downspout and fit the elbow, fastening it with sheet metal screws or pop rivets.

Drill a 3/4-inch hole in the wall of the barrel. This needs to be high enough so that you can place a bucket or a watering can underneath. Squeeze caulk around the hole on both sides. Build the spigot assembly and connect the spigot and coupling, and wrap Teflon tape on each of the threaded ends for a tight seal. Slip on a washer and insert the threaded end of the coupling through the hole from the outside. On the inside, put a washer over the pipe and fasten everything together with the bushing.

drill another hole in the barrel about 2 inches down from the top of the barrel. Build the overflow assembly and squeeze caulk around the hole inside and out and place a washer on the hose adapter. Push this assembly through the hole. Slip a washer and Teflon tape on the inside threads and tighten everything together with a nut. When you connect a length of garden hose to this overflow valve, you can direct some of the overflow into the garden after a heavy rain.

If your barrel has a lid, cut a hole where the new downspout elbow will direct water into it. Cover the hole with a piece of screen to keep mosquitoes out.

Finally, set the barrel back on the concrete blocks, make sure the downspout will direct water into it properly, and wait for the rain.

Check out the following videos for some ideas.

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