Before you spend your time and money designing and installing a rain garden, you probably want to know if it is something that is even feasible with your location.
Rain gardens are very adaptable, but there are three specific situations that I have come across in which a rain garden will not work.
There are also another five situations that are more challenging but can be remedied with some creativity.
I will cover these all in detail in the following two-part series.
A septic field is typically a series of parallel perforated pipes with gravel around them.
This system of gravel and pipes is used to disperse settled-out waste water into the soil.
Older systems can usually be identified by parallel slightly mounded ground about 3′ wide each. It is typically the first grass to green up in the spring and the most burnt-out grass in a drought.
A rain garden on top of a septic field would probably disturb and damage the septic field during excavation.
After installation the water in the rain garden may either drain too fast or not at all depending on the water conditions in the septic field.
Moreover, the roots of the plants would grow down into the pipes and gravel. These roots could potentially grown into the perforated pipes and clog the system.
This combination would be bad for the rain garden and also for the septic system.
The second no-go for a rain garden is the presence of a High Permanent Water Table in the top couple of feet of where you want to plant your rain garden.
This area is better suited to be a wetland than a rain garden.
Wetland plants can be used in this location to drink up and thrive in an area where grass and other plants will not, but extra rain should not be sent to this location.
If the water is permanently sitting a foot or two below your rain garden, where can the rain water in your rain garden go?
The only exception to this would be if a body of water is located next to where you want to put your rain garden.
In this situation it would actually be best management practices to install a rain garden to help act as a filter strip for the water that is then passing directly into the body of water.
If you think that you might have a high permanent water table, check out my post about how to figure out where your permanent water table is.
You need to have enough distance between your house and your rain garden that the water soaking down through the soil does not get pulled into the drain tile around your basement and into your sump pump.
If this happens you will end up making your sump pump work overtime as it re-circulates the water from the pit to the garden to the pipe to the pit.
The safe distance varies on the depth of your basement and rain garden elevation.
I have a post that goes into more detail on how to determine the distance from your house for your rain garden.
In addition to these three situations there are five more situations where rain garden can be used but my need some additional considerations. These can be found in PART 2