Your first step to installing a rain garden is to locate the water source(s) you want to use for your rain garden.
Your water source will probably depend on your motives for installing a rain garden.
And those motives tend to fall into one of three categories:
– Being Green
– Existing Drainage Issue
If you are choosing to put in a rain garden and do not have an existing drainage issue, then you are awesome.
Rain gardens are a lot of fun, and I don’t think you will regret your decision.
And as far as a water source, you will probably want to use your downspout(s) or sump pump as your water source.
If you have an existing drainage issue and want to try to use a rain garden as a solution you are still pretty awesome.
If you can identify the source of your problem, this is probably where you will want to start to locate your water sources.
It can take years of experience to understand the behavior of water on a property and if your situation is complex you may want to hire a professional to help you.
But 90% of the time drainage issues comes from one of three sources.
– A Sump Pump
– Surface runoff, or just runoff
*Technically downspouts are surface runoff from the roof, but I give them their own category because the runoff is already centralized and can utilize gravity because of its height above the ground.
If you are being required to put in a rain garden it is more than likely by a municipality.
You will probably be told which water sources you need to use.
You may still be awesome, but you probably don’t care about rain gardens and are upset that the stupid village is requiring one.
With all of these sources it is not as challenging to figure out where they originate as it is to figure out where they go.
This can best be done by observing them during a rain storm.
If you want to try to figure out the path on a dry day you will need to relay on standing water indicators, or you could use a water level or transit to find the topography of the area.
If it is possible, watching the water when it is actively flowing during a rainfall is my preferred method.
It really gives a great picture of all the hydrology going on in the area.
Surface runoff can be a little tricky but in general you want to look for any terrain that has either a steep slope or a long low slope above it, or an impermeable surface draining water to it.
Make notes of all these sources, especially ones that are in the area of where you would like to install your rain garden.
Then move on to Calculating Your Water Source.