RAINWATER HARVESTING

Sierra Club Sonoma Group

(707) 544-7651 http://www.redwood.sierraclub.

org/sonoma

Other ways to save water

Online Resources

http://ci.santa-rosa.ca.us/departments/utilities/conserve

http://ci.santa-rosa.ca.us/departments/utilities/conserve/Pages/ResidentialFAQs.aspx

http://cityofpetaluma.net/wrcd/waterconservation.html

http://www.rainbarrelguide.com/

http://www.harvestingrainwater.com/

http://groups.ucanr.org/sonomamg

http://www.coolcities.us/

http://rainwaterharvesting.tamu.edu/suppliers.html

http://www.oaecwater.org/education/roofwater-harvesting

http://www.aprainwaterharvesting.com/index.htm

http://www.youtube.com/watch?v=MGFDlkJOdaM

Run full loads of dishes and clothes, use low

flow toilets, disconnect your downspout and

divert the rain to your garden (at least 10 ft

from your house), create basins and berms,

inspect for plumbing leaks, sweep instead of

spray, eat vegetables instead of meat

(especially beef or pork), use SMART drip

irrigation, irrigate early or late in the day, turn

off water while soaping up and brushing teeth,

capture cold shower water and use for

irrigation, wrap garden containers with

insulating blankets, plant shade trees,

install permeable pavers,

apply thick mulch, plant

low water vegetation,

dry farm.

July 2009

What you’ll need:

Rain barrel; 2 spigots that will fit into 2 threaded holes

(1 at the top and 1 at the bottom); aluminum

downspouts; hose with male/female and shutoff fittings;

a hacksaw, pencil, and possibly hammer/nails, pliers,

plumber’s tape. There are various optional devices such

as: flexible downspouts and landscape pipes, leaf filters,

downspout diverters, etc.

Installation:

Prepare ground where the barrel will sit keeping in mind

that even small barrels weigh hundreds of pounds when

full. The ground should be flat and level and some

recommend using concrete blocks to place the barrel on

and although not necessary, it may be easier to access

the spigot at the bottom (you may also turn the spigot

so that it’s parallel to the ground.)

Estimate where the downspout will need to be cut –

check where the top of the rain barrel will sit and leave

room for the elbow. (The downspout will need to be

secured a few inches above the cut; do now or after

you’ve cut the downspout.) Cut the downspout with a

hacksaw. Attach the downspout so that it fits into the

elbow.

Attach the hose to the bottom spigot and leave the spigot

open; you will regulate the water from the end of the

hose. The top spigot is the overflow valve and some folks

attach a hose so that any excess water is directed to an

area that can tolerate more water. Make sure the valve

is open at all times. Take care not to strip the threads on

the barrel. Slide the barrel under the new downspout.

Photo credit: Winooski NRCD

Rain barrel installation tips

Rainwater harvesting captures precipitation and

uses it as close as possible to where it falls.

Rain may be directed so that it infiltrates the

ground (instead of running off) or it may be

collected from an impervious structure and

stored for later use.

More than two-thirds of the earth’s surface is

covered by water, but only 3% of this fresh

water supply is considered suitable for drinking

and agriculture. And, much of this freshwater is

locked up in frozen glaciers or it is located too

deep within the earth to be accessible. Our

supply is renewed mainly through precipitation.

A significant amount of rainwater runs off our

roofs and onto the streets and run-off may also

flood ditches and rivers. However, reasonably

pure rainwater can be collected from roofs.

Captured rainwater for land irrigation is an ideal

use particularly in Sonoma County where very

little to no rain falls over a period of 6 months

or more each year. Santa Rosa’s average

annual rainfall is 29 inches. Rainwater can help

to improve the health of your gardens, lawns,

and trees because it is considered soft due to

the lack of minerals and is unlike our surface

and ground water that takes up these

compounds as it runs through the soil.

What is rainwater harvesting?

Benefits of rainwater harvesting are many. It can

be used to grow food and may be stored for future

use when it’s most needed; it can decrease utility

bills, reduce groundwater demands, improve soil

fertility, increase local water resources… And, it’s

free! Water conservation measures are being

You may want to begin by estimating your home’s

water needs; both household and landscape.

Review your past and current water bills noticing

how much water was used in the winter vs summer

months. Typically, household use doesn’t fluctuate

much. You may then compare your usage to the

volume of rain falling on your house.

Calculating rainwater for 29 inches of rain For every square foot of roof, you will collect 0.6

gallons for every inch of rainfall; Size of roof eg 60 ft x 100 ft = 1600 sq ft;

Average rainfall eg Santa Rosa 29 inches; Total gallons from a 1,600 sq ft roof in Santa

Rosa: 1600 x 0.6 gals x 29 inches = 27,840 gallons*

*5-20% of runoff can be lost due to evaporation, wind, overflow of gutters

Determine the size of the catchment system and its placement

Many types of systems exist and you’ll want to

consider their size, composition and components,

as well as cost. You may choose a simple rain

barrel made from a recycled food barrel, a

multi-barrel system connected together near

the bottom with pvc pipes or hose, a cistern,

or a system that pumps water to the

landscape. Costs range from a few dollars to a

few thousand dollars. Rainwater catchment

systems must be placed on flat, immobile

surfaces (concrete blocks or sand are often

used) and below the gutter height to allow

gravity to move the flow of water.

Safeguards must be in place for small children

and animals; therefore, all systems should be

covered. Covers and filters also keep leaves

and other debris and mosquitoes from entering

the system. Also, the type of gutter system is

important as it may have lead soldering or

lead-based paints.

The operation and maintenance of rainwater

harvesting systems is the responsibility of the

property owner. Most cities require building

and plumbing permits along with backflow

prevention devices. Municipal inspections

typically occur during installation and

inspections of backflow prevention systems on

an annual basis. Ensure all applicable policies

and codes are being followed and permits are

in order. Other requirements may be

necessary and many government bodies are

only now drafting guidelines.

Most cities have water and energy

conservation rebate programs and some

include a rainwater harvesting rebate. They

also supply free water conservation devices

such as low flow showerheads. Contact your

city’s water conservation or utility department

for more information.

Why consider collecting rainwater?

Getting started

Policies and other information

implemented by every

municipality in the county,

so why not do what you can

and benefit from your own

efforts at the same time?

Catchment

devices may

include rain

barrels, cisterns

or storage tanks.