Collecting Rainwater: Water Supplementation by Harvesting Precipitation

May 03, 2018 - By Hayden Outdoors

Harvesting Rainwater


Collecting runoff from the roof of a home or outbuilding, for instance – is a common-sense, self-sufficient strategy that can reduce a property owner’s reliance on well water or a municipal water supply.

In one of the most straightforward rainwater-collection systems, water runs off an angled roof and into a rain gutter, which drains into a storage container; that container might be as simple as a barrel, or as elaborate as a cistern. Water is then available for garden irrigation or even household use, or as a reserve supply for emergencies.


Benefits of Harvesting Precipitation

The advantages of rainwater collection are numerous: rainwater is free and generally clean, and can create a water supply over which a landowner has complete control. Redirecting and collecting rainwater can also mitigate stormwater drainage issues that might otherwise exist.


How to Start Collecting Rainwater

Collecting rainwater, though, isn’t always as simple a matter as one might expect. A handful of states restrict rainwater collection, to varying degrees; restrictions are generally based on the premise that precipitation supplies water to streams and creeks, and that curtailing that supply has a negative effect for subsequent users with rights to use that water.

Some states, though, actively encourage rainwater collection, motivated in part by studies showing that such harvesting efforts have a positive environmental impact, reducing demand for municipal water and reliance on wells. Landowners interested in collecting rainwater should first research applicable state regulations.


Where Legally Allowed, Rain-collection Systems Include:


Rain Barrels

A gutter downspout simply empties into a barrel, which might be a barrel specifically marketed for this purpose, or a recycled barrel repurposed from another use. This simple strategy requires next to no engineering, but on the downside, even a 100-gallon barrel can fill quickly, resulting in overflowing and wasted water.

Storage tanks

In what is essentially an expanded version of the basic rain-barrel approach, a property owner can install a much larger tank – one holding hundreds of gallons – next to a home or building, with the collection pipe feeding water directly into the top of the tank. This is still a simple system, no more complicated than using a rain barrel, but it does require the installation of a large tank right next to a structure – probably acceptable for a barn or shop, but perhaps a drawback for a home.

Underground Pipes

In this more elaborate system, multiple downspouts (perhaps from multiple buildings) feed into underground pipes that supply water to a sizable tank, which can be located away from any buildings. With this system, more rainwater can be collected from more surfaces, but installing underground pipelines creates a significant expense. There are some minor engineering needs: pipe connections obviously need to be watertight, and the tank inlet must be below the height of the lowest gutter on a building that’s part of the system.


What to Know Before Building a Rainwater-collection System

Most rainwater-collection systems require next to no maintenance; even a relatively elaborate system with underground pipes carrying water from multiple rooftops is essentially just a pipe carrying water into a container. Any collection system, though, has significant potential benefits; a roof area of 1,000 square feet, in a region getting just 10 inches of rain a year, can result in more than 6,000 gallons of useable rainwater.