Downspout Drainage: Where Your Roof Water Should Actually Go
A lot of attention goes to keeping gutters clean, and rightly so, but the gutters are only half the system. Where the water goes once it reaches the bottom of the downspout matters just as much, and in the Lower Mainland's heavy rain, downspouts dumping water in the wrong place cause some of the most expensive problems a home can have.
Here is where roof water should actually go and how to check yours.
Why the discharge point matters
Your roof sheds an enormous volume of water in our climate, and every downspout concentrates a big share of it at one spot. If that spot is right at the base of the wall, the water soaks into the ground against the foundation, which is a leading contributor to basement moisture, seepage and settling over time.
The goal is to carry that water well away from the house, so it drains off harmlessly instead of pooling against the foundation or eroding the landscaping.
Where the water should go
Downspouts should discharge away from the foundation, either into a proper drainage system that carries the water off, or, at minimum, onto extensions or splash blocks that move it several feet from the wall and onto ground that slopes away. Many Lower Mainland homes tie downspouts into underground drain lines, which work well when they are clear.
The signs of a drainage problem are worth knowing: water pooling at the base of downspouts, eroded or soggy ground along the foundation, and downspouts that back up or overflow at the bottom during rain even when the gutters are clean.
When the problem is underground
If a downspout is tied into an underground drain and the water backs up at the bottom, the buried line may be blocked by roots, silt or debris. Flushing the downspout is the first check; if it will not clear, the blockage is likely in the underground line, which is a drainage job rather than a gutter one.
A proper gutter service flushes each downspout to confirm it drains and will tell you if the water is not getting away underground, rather than leaving you to discover it in a wet basement. If your downspouts discharge right at the wall, redirecting them is often a simple, high-value fix.