How do I attach gutters to a french drain, does the perforated pipe need to run entire distance?

Question

We have an ongoing problem with water pooling in a pseudo gulley between my house and my neighbors house. We have water that drains from the backyards to this area, along with two gutter roof drainage pipes on each house draining to this little area. The distance from the top of the proposed drain pipe to the sidewalk is roughly 70 feet. The green dots on each house are the gutter points.

Every time we run the sprinkler system, or get a minute amount of rain, this area between the two homes turns into a lake. We cannot mow the yard for at least 3 days after because of the poor drainage and tearing up the grass. We want to route this water away and figured the best way to do so would be using a French drain system. The bulk of the collection/pooling area is in the box framed by the 4 green dots (the gutter spouts from the roofs of the homes). There really is not much of an issue with drainage in the area between the sidewalk and the front of the homes (the general area where the CATV box is).

When this lake system develops, our home (which is on a slab), starts getting moisture at the edges inside. In order to prevent mold, this really is a must-do.

I have the following layout of my house in my subdivision.

I am exploring the possibility of installing the prefabricated pipe with the styrofoam peanuts with the sock around it to basically do it all for me.

My main questions are:

1. If I were to run the pipe (the blue thing in the picture) the distance from the top edge of the houses to the sidewalk (~70ft), do I need to run this prefabricated stuff the whole way? This stuff runs like $45-50 per 10ft, so i would be looking at around 300-350 at least for just the pipe. Would it be possible to run it through the area that needs to have the water collected and then connect it to a standard pipe that runs the rest of the way to the sidewalk, where it can empty down to the storm drain?

2. I would [prefer] to have the gutter systems dump directly into the drain pipe. Is that doable? What would I need in order to do that?

3. I have heard of people using PVC pipe for this, is that really much better? I imagine the pipe inside is a lot smoother so it is easier for crud that builds up to get flushed out - but once again, not sure if the tradeoff is worth it.

I don't want to be a cheapskate on this, as i want to do it the right way. However, if I can save $200 by skipping running the prefab perforated tubing the entire run, I would like to!

Answer 1

You are trying to combine two systems: 1) collection of ground water, and 2) collection of roof drainage. This is a bad idea...don’t do it.

1) Perforated pipe is used to COLLECT ground water. The concept behind the use of perforated pipe is that water flows in the direction of least resistance. That is to say, ground water near the perf pipe will flow into the pipe and the remaining water will flow to that area. Then, the process continues until all the ground water has been collected by the perf pipe and carried away.

Introducing water from your roof into the perf pipe will prohibit ground water from entering the perf pipe system. (You’re defeating the purpose of the perf pipe system.)

2) Solid pipe is used to TRANSPORT water. The water you’ve collected from your roofs should be transported to a storm sewer system...probably in the street.

When you combine the systems, the water from the roofs will not only prohibit ground water from entering the perf pipe, but will introduce roof water into the ground water system due to a hydrostatic “head” pushing water OUT the perf pipe. (Water can flow both ways through those holes in the perf pipe.)

Recommendation:

I’d use perf pipe where you have ponding water between the houses and then use solid pipe to transport it to the street storm system. I’d also use solid pipe to collect your roof water from your gutters and downspouts and extend that solid pipe to the street storm system. I would NOT combine the solid pipes, because an abundance of roof water can backup into the ground water system and prohibit it from draining.

Btw, when you install the perf pipe, be sure to put the holes on the bottom...not the top. You want the ground water to enter the pipe as soon as possible. If you put the holes on top, then the ground water has to fill up to the top of the pipe before it can spill into the pipe.

Answer 2

Landscapers and contractors deal with this by using four inch perforated drain pipe with a woven sleeve that prevents dirt from blocking it. You can buy T's and forty five degree joins. It is much cheaper than perforated pipe and can be bought at most home improvement stores.

It just happens that your standard down spout will fit inside a four inch diameter pipe. Just tie the sleeve around the downspout or you can buy a custom plastic fitting to do adapt the downspout to the pipe.

Lay the perforated four inch pipe in a trench at least six inches deep and back fill with soil, then top with sod. Try to add a slope to the trench towards the street. Laser levels are helpful for this. You don't need a lot of drop, even a few inches over twenty feet is more than enough.

You can make yourself a cheap dry well by digging a hole underneath the pipe about two feet deep and the width of a plastic bucket that is commonly used for drywall. You can buy these but you might have some lying around. Cut out the bottom and insert in the hole. Fill with large rocks that will not compact. Cover the top with landscape fabric to prevent soil from plugging it up with time. Then the perforated pipe goes over this. You can add as many of these as you like underneath where the drain pipe runs.

A regular rainfall should drain into the pipe and slowly move downhill towards the street. Larger volumes of water will also drain into the dry wells.

Revised drain plan