Installing Downspout Drain Lines

32 responses

  1. Alex G
    September 29, 2012

    Hi Tim,

    Re: "I usually dig a trench about 12 to 14 inches deep for downspout drain lines." -- would the same depth be sufficient in Canada where I live? I was talking to somebody at Home Depot and they repeatedly warned me that no underground drainage pipe should be closer to the surface than 4 feet (for the fear of freezing).

    Would appreciate your opinion -- I am about to start a drain pipe burial project, don't want to dig too much, but if freezing is a concern, I'd probably have to go deeper than 4 feet.


    • Tim Carter
      January 6, 2013

      Alex, your question requires lots of typing, plus I have some questions for you so I can give you the correct answer(s). I only do pithy answers here in the comment section. If you want to protect the investment you have in your house and not waste time or money *hoping* you make the right decision, you should talk to me on the phone for just 15 minutes. It'll be the best investment you've ever made in your home!

      • Kathy
        May 14, 2013

        Hi Tim
        We have a crew who is currently installing the under ground spouts, I noticed they have only dug down maybe 8" we also live in Canada and it can really get cold! I would like to know the proper way to install before our guys leave....thanks

      • Tim Carter
        February 27, 2014

        Arrange a phone consult with me.

  2. Zorena afroze
    September 2, 2013

    I have a house in the country area , I leave lots of trees .i would like to know how to bury downspourt.

  3. Harold Haver
    March 30, 2014

    Same question on the underground horizontal drain lines for down spouts. My experience has been the horizontal lines freeze (glacier style) and eventually block the pipe closest to the exit point. ALL lines eventually exit at ground level away from the house and therefore the ground freezes HARD in that vicinity...thus the glacier ice. HOW do you prevent this? Add a heat tape? And IF yes, one has to remember to turn it on/off as the conditions change. Oftentimes it is very cold with NO snow melt off the roof, so heating the pipe is not necessary. Will the heat tape damage the plastic pipe? What IF Schedule 40 was used? Thanks in advance for your advice. We are doing a NEW home build and want this to be taken care of permanently. Plus, some of the drain lines will go "under" paved areas like a driveway and/or patio. Therefore, got to get this right.

    • Tim Carter
      March 30, 2014

      Install a wye fitting and above-ground clean out far upstream where you can open it and add a very salty brine hot-water solution IF it does freeze.

      Brine should melt the ice and open the line.

  4. John Matt
    June 17, 2014


    You recomend 4" diameter pipe, but I am trying to determine how many downspouts I can run in one 4" diameter pipe. I live in KY and the way the lot is set up, I will have plenty of slope and it will be draining into a creek, but the square footage of my roof is approx. 4500 sq ft. This is a new construction and I am trying to get the drains installed before I sow my lawn this fall. I have had people recomend running a 4" line for each drain and others saying that all of them could drain in one pipe. Thanks for any help that you can provide.

    • Tim Carter
      June 18, 2014

      Put half the roof on a 4-inch pipe and the other half on another 4-inch pipe. Where the two pipes meet to run to daylight, increase the pipe size to 6 inches.

  5. Rebecca
    September 3, 2014


    I need to run the roof runoff from the gutters to a lake behind my house. I currently have the gutters draining into 4" PVC and then into 2 lines that are 6" PVC. The roof is 5000SF. The PVC is buried. during heavy rains one of the runs to the lake doesn't seem to keep up. The rain overwhelms it. The landscaper says that it's because the run drains into the lake below the waterline. Does this sound right to you?

    • Tim Carter
      September 4, 2014

      Yes. If the outlet of the pipe is UNDERWATER, then the water pressure in the lake is reducing what can run through the pipe. The outlets of the drain pipes MUST be open to the air for maximum flow.

  6. Steve Caldwell
    September 9, 2014

    i guess it takes you some time to respond to questions?

  7. Mike
    October 13, 2014

    Hi Tim,

    Will pop-up emitters freeze up in the Midwest (northwest Missouri)? If so, what is a good alternative solution? Thanks in advance.

    • Tim Carter
      October 15, 2014

      Anything that traps liquid water in a pool where it can then freeze is bad jujumagumbo. The water needs to flow across the surface and soak into the soil.

    • David S
      March 8, 2015

      Mine did.

  8. Blair Gilbert
    October 30, 2014

    I live near Detroit Mi, we have lots of snow and frost. We've been installing underground downspouts in our area for over 20-years. Our area is mostly clay so we need to take the water away from the home, to keep the basement dry. I sell a system with a filter installed under the downspout (just before the system inters the ground), then go at least 10-ft away from the home to a 4" pvc tee, a strainer on top to discharge water installed over a post hole filled with pea gravel. The tee over the gravel (what we call a mini French drain) prevents the system from holding water for very long.


    I'm a college-trained geologist with a specialty in hydrogeology - the study of ground water. I'm sad to tell you your system has virtually no ability to dissipate water because the deeper you go in clay soils - into the B horizon - there's LESS ability for the water to move through the clay. What's more, most of the post hole is filled with stone so there's very little capacity to hold water. I'm afraid your system is based on bad science.

  9. Jonathan Lozier
    July 30, 2015

    Jonathan Lozier
    Great website and very informative. I plan on installing a french drain with 4" perforated HDPE approximately 30' in front of my house. I own a backhoe which is necessary in order to dig through my very heavy clay soil. I have plenty of room for pitch and the overall length is rough 150' around the back of the house. I plan on burying the gutter downspouts with 4" solid HDPE and having it run right over top over the perforated out to day light, essentially stacked.I figure dig one hole for several purposes, the roof water is not going into the french drain pipe it will be contained within its own solid pipe. One 4" solid pipe for each down spout. Question: I live in upstate NY and the winters are rough, I am very worried about the 'glacial effect' within the drain pipes, how do prevent that? do I have to dig down 4'?
    Thanks for your time

  10. Dan Hinds
    September 28, 2015

    First let me say " Thank you " for the time & effort you freely invest into this site.
    I recently ripped up all the grass (weeds) in the backyard of our new house. We live in Pennsylvania area incase that may effect your opinions. Currently our rain spouts empty where they end and I know this is the worst possible case. While the backyard is nothing but dirt Id like to install a drainage system to remove water away from the home. Backyard is approx 60ft from back of home to rear fence, slightly sloping away from house. Outside of rear fence is a 20ft evesmeant between the neighboring yard. My plan is to install a drain box w/grate under each downspout, each traveling to one of Two main 4in PVC (one main for each side of house) each main will end discharging into one of two buried perculating dry wells.
    My soil makeup is mostly Clay, I did a Perc Test by digging 4ft deep hole with a post hole digger & filling with water, after three days the water has dropped maybe 2inches. so my concern is will the drywell perc system even work for me? If not what might you suggest?? I'm also planning on putting a 12x12 shed in the lowest back corner of the yard on a concrete slab, have the area dug out to begin preparing the base for the shed. It recently rained and I noticed the hole filled with water in the one corner which sat pooled for some time.. I need to do whatever I can to address drainage prior to pouring cement for shed slab and seeding the lawn. I know this is a lot to take in but I figured the more information i give the better you might envision my situation. Thanks in advance for any help your able to offer.

  11. Francis
    May 9, 2016

    The fact that people in the southwest (of the United States) don't collect rainwater is not surprising because it's actually illegal. "Water rights" is the "third rail" in politics in the west. If water falls on your ground and you don't have rights to it, you have to let it go downstream.

  12. Patricia
    June 22, 2016

    We bought a house ten years ago previously owned by wanna-be gardeners who installed a lot of "stuff" we are just now discovering. One of those things is a downspout that goes into the ground. We have no idea where the water is draining; that side of the house is very close to our neighbor's property. Would the City be able to tell us if that pipe flows into the City sewer system? This house was the first built in the neighborhood...Are there any other clues we could look for? The house sits on a slight hill so the logical thing would be a pipe that comes out somewhere near the street/curb near that side of the house, but not seeing anything like that...

  13. Del
    December 8, 2016

    Do the drainage lines need to pass under or over water lines, coming in to the house, or does it not really matter

  14. Evan
    January 4, 2017

    The reason rainwater is not collected in most of the Southwest is because it is illegal. The author should do a little research on the lack of a right to collect rainwater in most southwestern states before spouting his mouth off about how we don't know what we're doing. Capturing rainwater in drought areas makes the drought worse.

    • Marie
      January 25, 2017

      Since you have done research perhaps you can tell us which SW states don't allow rainwater collection? I live in San Diego and we can collect rainwater. Also where is the author "spouting his mouth off" about how we don't know what we are doing?? I thought he was providing free information to people who need some help or ideas on various topics. If you read the article more slowly you might catch the line, "If you're permitted to collect and store rainwater, this water can be easily collected".

  15. Mark Karchon
    February 12, 2017

    Hi Tim, I justed moved into a house that is 15 years old and have found the black corrugated drains are crushed in different spots. The rest of the drain is ok. I know this because I dug one up and used a camera on the others. My question is if I dig up only where the crushed drain is and replaced it with PVC, do you think this will suffice? Again the corrugated pipe has been there 15 years.

    • Tim Carter
      February 12, 2017

      Just SUCK IT UP and get rid of that crap. Abandon the Black-Pipe-of-Death and put in the pipe I talk about in the column above.

      Do that and you'll NEVER have issues.

  16. STEVEN RE’
    May 21, 2017

    HI TIM,


    • Tim Carter
      May 22, 2017

      One foot is plenty deep. You'd only need to upsize to 6-inch pipe if you have a huge roof like I did on my home. My roof was over 5,000 square feet of surface area.

  17. Steven Re’
    June 19, 2017

    Hi Tim an thank you for your response. I have another question. Where I terminate the pipe I am going to dig a 3 foot deep hole where the t-connection will be placed. I know I need to put gravel at the bottom of the hole. My question is how high should I have the gravel rise. Should I have it to the bottom of the t-fitting so as not to have any dirt blocking the water draining into the gravel. I am concerned that if I fill just the bottom with the gravel and then dirt on top of it, the dirt may cause a blockage or prevent the water from draining smoothly from the bottom of the t fitting.
    Thank you

  18. Jeff meiller
    July 12, 2017

    I have had an ongoing issue with drainage from storm water. It seems all my downspouts empty behind my house on one side of my property. Consequently this area is almost always to saturated to cut grass or even walk on it. This is a large house, (ranch style) of about 6200sq ft so has a lot of roof runoff. My questions are: is it unusual to have all drainage on one side of house? Seems It would make more sense to have half on one side, half on the other. Also, do drain pipes have holes or perforations to catch runoff in front yard ? I think maybe when we had a inground pool put in 4 years ago one drain line got broken, buried or both. Not sure who to call to even begin to diagnose the problem...?

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