Your system will include the following:

  1. Catchment Surface: This would be your roof, driveway or parking lot- any impervious surface from which you want to collect water.
  2. Debris Exclusion: These are your gutter guards and/or debris excluders (i.e.; "leaf eater," "leaf beater," downspout diverter). They keep the larger debris out of your downspout and tank, which helps maintain a high quality of water within the tank.
  3. Conveyance System: This is your gutters, downspouts and piping which convey the water from your roof or impervious surface to your tank.
  4. First Flush: This is a simple system that collects and/or diverts the "first flush" of water from your impervious surface, keeping it out of your tank. The initial runoff from the first rain of the season washes your roof or other impervious surface of the debris that has collected over the dry season (i.e.; dust, pollens, bird droppings, bugs, etc.). This again contributes to high quality water in your tank. First flush water can be directed to a rain garden or to an existing drainage system.
  5. Storage Container: This is one or more tank or barrels. This can be above or below ground.
  6. Overflow: When designing a system, you always want to include an overflow, so that excess water will be directed out of the tank when it is full (vs. backing up the system and spewing out uncontrolled). Overflow can be directed to another tank or barrel, in a "daisy chain" design, into the soil via a rain garden, and/or to the existing drainage system.
  7. Outlet & Distribution: How will you use the water in the tank? This can be as simple as filling a watering can from the tank's outlet, to connecting to an irrigation system. This can include a timer and/or pump.
  8. Mosquito & Critter Proofing: Screens must be installed at any openings in your system to prevent mosquitos and other critters from entering your tank and breeding.
  9. Operations & Maintenance Plan: When designed properly to ensure the best quality of water coming into to your storage container (see #2 and #4) and keeping mosquitoes and other vectors out (see #8), rainwater harvesting systems generally do not need a lot of maintenance. But it is good to have a plan. This should include cleaning roof gutters and debris excluders once annually or as needed, checking your tanks when empty to see if sediments are accumulating and cleaning them out as needed, and visually inspecting fittings, valves and irrigation lines to make sure there are not leaks or blockages. 
  10. Signage & Safety: You want to be sure that your tank is secure and that no one, in particular no children, can fall in to it. Locking lids are available for this purpose. A sign should be posted by the lid that states: "Confined Space- Do Not Enter." It is important to mark any spigots, hose bibs and irrigation lines coming from your system with a "Non-Potable rainwater - Do Not Drink" sign and/or tape for safety purposes. These signs should be in English and Spanish where appropriate. A Backflow Prevention Device is also required to protect the municipal water system from any untreated harvested water. For more information about this aspect, click here.

View our Rainwater Harvesting Schematic here (click on image below to enlarge):

Created by Jeffrey Adams

First Flush System Parts
Backflow Prevention Device
'Daisy chain' system on two barrels
Leaf Beater (debris exclusion)
Leaf Eater (debris exclusion)