Where the Water Goes:
Downspout Drain Lines, Old Storm Drains, Dry Wells and Yard Drains
The downspout goes into a pipe in the ground. After that, nobody at the inspection can see where the water ends up, and sometimes nobody knows.
At one Portland house, the original clay or cast-iron storm drain standpipes were still carrying the downspout water away, more or less where the builder put them generations ago. Down the street, other houses have their downspouts aimed at the lawn, a buried line to a dry well, or a pipe that goes into the ground and then nobody knows where.
Roof water is a lot of water. In Russ’s recent reports, 53 of 269 houses had a finding on the drain lines or storm drains the downspouts feed, separate from the gutters and downspouts themselves. (Gutters, elbows and splash blocks have their own post: the most common downspout problems.)
Old storm drains in older Portland houses
Many older Portland-area houses were built with downspouts running into underground pipe: clay tile, cast iron, or later ABS plastic. In parts of Portland, those pipes were tied into the combined sewer, which carries both sewage and stormwater.
From 1993 to 2011, the city’s Bureau of Environmental Services ran a downspout disconnection program to take roof water out of that combined sewer and cut the overflows into the Willamette River and Columbia Slough. Tens of thousands of homeowners took part. Disconnected downspouts were cut off above the standpipe and turned onto the yard, and the standpipe was capped.
So a house in close-in Portland might have any of these: an original standpipe still in use, a capped standpipe and a downspout onto the lawn, or a mix. Russ’s reports show the mix. In one Portland house, some downspouts drained into underground lines and others bypassed abandoned drains and dumped onto the ground. In another, most of the storm drains were abandoned and roof water was draining into the yard. A West Linn house had storm drains that weren’t in use and weren’t capped, which lets debris fall in and clog them.
Drain lines nobody can trace
A finding that keeps coming up in Russ’s reports is some version of “termination unknown.” A Vancouver house had downspouts running into what appeared to be drain tiles, with no clear destination for the water. A house in The Dalles had drains added after it was built, and the end point wasn’t readily visible. A Portland house had new downspout drain lines, and the report recommended asking the seller or a drainage specialist where they go.
That matters because a buried drain line has three possible fates, and you can’t tell which from the yard:
- It runs somewhere sensible, like a dry well, the curb, a ditch or a storm main, and works.
- It runs somewhere sensible and is clogged, crushed or full of roots, so it backs up.
- It’s broken a few feet from the house, so it soaks the soil at the foundation.
The third one looks exactly like the first from above ground. When a house has a damp crawlspace or a leaking basement corner below a downspout, a broken drain line is one of the first suspects. The posts on crawlspace water intrusion and leaking basements cover what that water does once it gets in.
Dry wells and yard drains
A dry well is a buried pit or perforated tank, often filled with gravel, that collects roof water and lets it soak into the ground. In sandy or gravelly soil, it works. In tight clay soil, which is common in parts of the Portland metro, a dry well can fill faster than it drains and back the water up the pipe. Most are invisible from the surface, and many have no record of where they are or how big they are.
Yard and area drains handle surface water. A Gladstone basement walkout stair had no area drain at the bottom, so storm water was draining into an open hole. A Battle Ground side yard was pooling even with surface drains installed. A Tigard backyard had standing water along the foundation, and a Gresham yard had no drainage at all and was wet and muddy. Beaverton downspouts ended over open plastic catch basins instead of sealed drain connections.
The top of the pipe: what goes wrong where you can see it
The visible end of a drain line has its own common failures:
- The downspout pulled out of the drain. The most common one in Russ’s reports, turning up from Beaverton and Sherwood to Brush Prairie. The roof water lands at the foundation instead of in the pipe.
- The drain inlet below grade. Seven houses had drain tile that ended below the soil surface. That hides the connection and lets soil and debris wash in.
- Damaged or cracked inlets and fittings. Vancouver, Woodland and King City reports found cracked or broken drain tile at the downspout.
- Exposed plastic drain pipe. ABS storm pipe left above ground in Ridgefield, La Center and Portland, where sunlight breaks it down over time.
- A downspout that never made it into the drain at all. In Vancouver, a downspout stopped short of its drain connection.
- Leftovers. In one Portland house, a wood spacer block from installation was still wedged behind the downspout drain line.
Uncapped risers count too. A Lake Oswego house had an open riser on the sewer or storm drain system, which lets debris in.
Real Inspection Photos
Drain Line Findings From Russ's Inspections
Old standpipes, abandoned drains and the visible tops of buried drain lines at Portland-area houses.
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Most of the storm drains at this Portland house were abandoned, and roof water was draining into the yard. -
Some downspouts here ran into underground lines, while others bypassed abandoned drains and discharged at the surface. -
This downspout ended over an open catch basin instead of a sealed connection to the underground drain. -
The bottom of this basement walkout had no proper area drain, and storm water was draining into an open hole. -
A downspout pulled out of its drain inlet, so roof water lands at the foundation.
What the inspection covers, and who checks the buried part
Russ follows each downspout to where it ends, notes whether it goes into the ground, onto a splash block or onto the yard, and checks the connection and inlet. He looks for exposed or damaged pipe, open risers, ponding, and signs of water at the foundation, in the crawlspace and in the basement. When the termination can’t be found or the pipe is original, he says so.
The pipe underground is outside a visual inspection. A drainage contractor or plumber can run a camera through a storm drain line the way a sewer scope runs through the sewer line. When a house still drains roof water into old standpipes, it’s worth asking whether they connect to the sewer, because the sewer scope may see them from the other end. The seller’s disclosure and the city or county may have records of disconnection or of a permitted dry well.
- Follow every downspout to where it ends: ground, splash block, or a pipe in the ground
- Check that each downspout is seated in its drain inlet and not pulled out
- Look for capped or open standpipes near the foundation
- After a rain, look for water pooling near downspouts or along the foundation
- Ask the sellers where the underground drains go, and whether the downspouts were ever disconnected
A downspout that goes into the ground is only as good as the pipe you can’t see. In Russ’s reports, the common findings were downspouts pulled out of their drains, inlets buried below grade, and drain lines whose end point nobody could find. A camera inspection by a drainage contractor is how the buried part gets checked.
The guide to gutters and downspouts on Portland homes covers the rest of the roof drainage system. To set up an inspection, you can book online.
Downspout Drain Line FAQ
