With all of the recent rains, we need to mention a few things about French Drains and our Gutters. Let’s start with French Drains and what they are. Here is a picture of a basic kit to install this type of “drain”. It is basically a plastic box with a grating and a hole for a perforated pipe to connect in order to disperse the collected water down the length of the pipe and into surrounding ground. The pipe itself is surrounded by gravel so there is some area for the water to go into. These “drains” do not connect to ancillary drainage systems, piping or the like.
The problem that we have had lately is an abundance of rain and the total saturation of the ground to the point that whatever water is collecting in these French Drain systems has absolutely no where to go. They were initially located at points around the property that tend to collect water, mostly due to ground sinking. But, here of late, they have themselves become places for water to collect due to their inability to channel water into an area that can absorb it.
It may require that we rethink these systems and/or spend some money to redo them or make sure that they were done properly initially. Without the proper amount of gravel surrounding the pipes, two thinks will happen: 1) there is no vacant areas for the water to seep into and 2) with dirt right next to the perforated pipe, the holes will eventually get plugged and the drain system itself turns into a water collecting point.
Gutters – With the amount of rainfall we have had lately, even with a completely clear gutter system, there is no way that the gutters can hold the entire amount of water falling. Also, add in the fact that these gutters are connected to the neighbor’s gutter systems, you have just multiplied the total amount of water we expect a 4″ gutter to channel away.
For the sake of illustration, let’s figure how much rainwater we could collect at a rainfall of 1/2″ per hour across 600 square foot area. When you plug these numbers into the equation, you get a total rainfall volume of more than 187 gallons within that one hour. If you use a rainfall of 1″ per hour over the same 600 Sq Ft are, it changes to over 374 gallons. Multiply that by the number of houses tied into the same gutter system and you get the idea that you can only put so much water into a 4″ gutter system, with 4″ downspouts. That’s why the water runs over the sides of the gutters during heavy rainfall.