I'm building some "dry wells" to handle the water coming from the gutter downspouts. The water will be diverted underground to a large underground drainage pit.

1. What is the purpose of a "catch basin"? Is a "catch basin" needed coming off the downspout?

2. I see that you can use pvc drainage pipes (similar to house plumbing drainage pipes) to move the water from the downspout to the dry well OR you can use corrugated piping for the same purpose? What are the pros/cons of one type of pipe vs the other? I don't plan on using the non-perforated variety of either.

Thank you.

I usually do not do what you are describing because I'd rather use an extra section of downspout to get the water at least 5' always from the home, is this area graded away from the home?

To answer your question I would use PVC. The smoother inside of the pipe will be less likely to collect leaves and debris and it can be snaked if it gets stopped up. Just lay the pipe and use a 90 ell to turn up a short piece of pipe, which the downspout will fit into.

I, like Bob, wouldn't recommend a dry well if any other alternative exist. It won't take but just a short time to fill up a drywell with the water off your roof. After that you are left with all the rainwater going into the ground at you house.

Why don't you tell us a little more about your situation?

You can find the rainfall tables in the plumbing code. Say it's 3"/hr and then you have to use the projection of the roof collected and then convert to gallons to help size the dry well.

A "catch basin" is just that, it catches things like leaves before they get into your drainage pipes. It's basically a grate over a sump, but the pipe exiting the sump is higher than the bottom. So the leaves fall to the bottom and the water exits out the pipe. Occasionally, you lift the grate and clean the leaves out.

The smooth pipe has less friction and is less likely to clog with debris.

You do need to slope the pipes, so a small section of corrogated will be needed at the catch basin and the entrance to the dry well.

From the ICC Plumbing code:

You need 12" of rock-free dirt in 6" layers.

Slope 4" pipe at 1/8" per foot.

Cleanouts in direction of flow. Cleanouts in every change in direction.

For some of the downspouts, where the grade is appropriate, I'll be extending the downspout about 5 feet away from the house. In other areas, the grade doesn't lend itself to that, so I'm building some dry wells. The dry well will consist of a pit that holds around 4-5 cubic yards of drain rock. It will be capped off with 12-18" of dirt. Filter fabric will help keep the dirt out of the drain rock. Any advice/ideas?

How about posting some pictures of where you intend to put the drywells.

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Originally Posted by homeskillet66

I'm building some "dry wells" to handle the water coming from the gutter downspouts. The water will be diverted underground to a large underground drainage pit.

1. What is the purpose of a "catch basin"? Is a "catch basin" needed coming off of the downspout?

2. I see that you can use pvc drainage pipes (similar to house plumbing drainage pipes) to move the water from the downspout to the dry well OR you can use corrugated piping for the same purpose? What are the pros/cons of one type of pipe vs the other? I don't plan on using the non-perforated variety of either.

Thank you.

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I am looking to divert gutter water from the house via drainage, do I need a dry well? I am trying to keep water from my basement.

1. Catch basins. They tend to have a deep pocket and a raised exit. Debris flows to the bottom of the bocket and will not flow into the pipe. The escess debris get cleaned out of yhr catch basic periodically.

Example. Raun gutter, grate, catch basin. That catch basic cathes the debris before it gets to the pipe.

2. Corrogated piping has friction. It's easy to use. Easy to slope. The dry well is just that DRY. If it is not dRY, there is no where for the water to collect and percolate into the soil. So it's a buried tank in the groound with an open bottom.

Change in diretion reqires a cleanout.

You don't fill a dry well.