Rainwater Harvesting

What is Rainwater Harvesting?

RainRainwater Harvesting is the capture and collection of run-off water, siphoning it into a storage container, and re-using that water in a myriad of different ways. Harvested rainwater can be used for irrigation, gardening, and in some cases livestock. With proper filtering it can also be used as drinking water.

Rainwater harvesting provides an alternative water source during times of environmental stress such as drought by reducing demand on aquifers, wells, and groundwater levels. Rainwater is traditional much freer of salts and other natural and man-made contaminates then groundwater.

Up On The Roof

RainYour roof is your first consideration. What kind materials your roof is made of, and/or coverings applied to your roof can affect the water captured.

You should always first check the materials and chemical compositions of any coatings used on your roof before beginning to harvest water from it.

Gutters play a huge role in the distribution of water from your roof to your tank. For this reason they need to be cleaned on a regular basis. Regular cleaning of gutters allows for unimpeded flow of water and far less debris and particulate in the water collected in the tank.

Additionally all pipes, hoses, and fittings from the gutters to the tank should be made of materials that are safe for your intended water usage.

Square Footage Matters

FootageWhen choosing a rainwater harvesting system, in particular the collection tank, the volume of rainfall and water usage needs to be taken into account. As rule of thumb 1 inch of rain on a 1000 square foot roof will yield 650 gallons of water. (1 - 1000 – 650). The size of your tank should be equal to the capacity to collect water and the regularity in which the water is drawn from the tank.

So, if you have a 2000 square foot roof in an area with an average rainfall of 7 inches a year you could collect 9,100 gallons of water a year.

Tank Size & Placement

Tank sizeNow, considering that 9,100 gallons of water, what kind of space do you have for your tank? Consider that a 3000 gallon tank has a circumference of 102 inches (8.5 feet) across. It is also 93 inches (7 ¾ feet) high. That physical “footprint” needs to be taken into account.

Thus you need to use enough water to empty that 3000 gallon tank twice so it can be filled a third time, or store that water in an alternative tank or containers.

Keep in mind the tank need not be directly under the gutter nor next to the structure. Water can be brought from the gutter via pipes and flex hose to a tank that is offset from the structure. Tanks can even be installed underground provided they made of proper materials such as high density plastic or fiberglass.

Drawing Water From the Tank & Filtration

Tank FiltrationIn terms of source water (gutter) to tank filtration, a simple screen filtering system attached somewhere between the gutter “outlet” and the run of pipe or flex hose. This will substantially reduce the levels of debris in the rainwater before it is ever channeled into the storage tank. Additionally what sediment and small particulate that remains can be substantially alleviated by drawing water from the tank using a floating draw-off mechanism rather than drawing water via gravity from the bottom of the tank.

Water can be drawn from tanks in two ways, the first being gravity. A fitting is placed at the bottom of the tank with a manually operated valve, a pipe or hose is attached to this valve and when that valve is opened water can freely flow through it. This manner of drawing water is efficient as it uses no power, but flow pressure is not comparable to what most people are used too. Some filtration options are available using the gravity feed method. Gravity feed is not viable for tanks placed underground.

The second method of drawing water from the tank involves either a floating draw off mechanism or a gravity fed fitting at the bottom of the tank, piped or hosed to an electrical pump (solar pumps are available). When the pump is engaged water is removed from the tank at an exponentially quicker rate that gravity-feed, based upon the horsepower of the pump. Because of the force of the water moving through the pump some very effective methods of filtration are available.

What Can You Do With The Water?

FlowerOf course what you do with the water depends on how it was or was not filtered. We never recommend that rainwater be consumed without being filtered to the point of being considered “potable water”.

Harvested rainwater can be used for gardens, irrigation, creating ponds and wildlife habitats. It can be used for washing cars, pressure washing homes and driveways, mixing cement for household improvements. There are so many things you can do, and all of it takes stress off your local water supply.

Please browse through our selection of RAIN TANKS and find the right one that fits your needs and catches your eye, any questions please contact us, here are a few pictures of a simple rainwater harvesting set up.


North America water Spawn NWBOC Wbe Certified California Rural Water Association AIA ARCSA Member NFPA AWWA US Green Building Council Member