Downpipe unblocking

How a rainwater drainage system works

A rainwater drainage system is more than just the pipe on the outside of your house. Rain first runs into the gutter, which slopes slightly towards an outlet. From there it flows into the downpipe, usually 70 to 100 millimetres wide on an ordinary house. At the bottom, the pipe disappears into the ground, often with a bend and sometimes via a leaf guard or an access cover.

Below ground, the water can go one of several ways. In many older neighbourhoods it runs into the combined sewer, together with the waste water from the house. Newer neighbourhoods often have a separate system, with a dedicated pipe for rainwater. And more and more homes are disconnected from the sewer: the downpipe then empties into the garden, a water butt or a soakaway. Each system has its own weak spots.

Flat roofs work slightly differently. The outlet sits in the roof surface itself, usually covered by a gravel guard or leaf guard, and there's often an emergency overflow through the roof edge. If water is coming out of that emergency overflow, the main outlet is blocked.

Responsibility works the same way as for the ordinary sewer. In general terms, the downpipe and the pipe on your own land are the owner's responsibility, and the connection under public land usually falls to the municipality. Exactly where the line is drawn varies between municipalities. If you rent, your landlord is the first person to contact.

Why a downpipe gets blocked

From above: leaves, moss and nests

Most blockages come down from the roof. Autumn leaves, moss washed off the roof tiles, twigs and seeds collect in the gutter and are swept into the pipe by the next shower. In spring, birds like to nest in the gutter or near the outlet. On a flat roof, gravel washes in if the gravel guard is missing, and a stray ball can lodge right in the bend.

Underground: sand, roots and subsidence

Concrete roof tiles shed sand over the years, and it settles in the underground pipe. Then there are roots, which grow in through an open joint, just as they do in the foul sewer. If the ground around the connection subsides, the bend at the bottom of the pipe can come loose or kink. The water then no longer drains away but soaks into the ground right next to the foundations.

Frost

In winter, ice can completely seal off a pipe that's already half blocked. Water that freezes in the pipe expands and can split a zinc or plastic downpipe. So after a spell of hard frost, check the pipe for cracks and leaking joints.

Blocked downpipe? How to find the blockage

The way the water behaves gives away where the problem is:

• The gutter overflows, but nothing comes out of the pipe. The blockage is at the outlet or at the top of the pipe.
• Water spurts out of a joint halfway down. The pipe is blocked below that point and full of water up to the leaking joint.
• Water bubbles up at the bottom or stands around the pipe. The underground pipe is blocked or has subsided.
• In heavy rain, water comes up out of a drain in the garden. If you're connected to the combined sewer, that may be backflow: the public sewer is full and the water is looking for the lowest way out.

If water is standing on the patio or driveway, the outside drain is often blocked: its grate or silt trap is full of leaves and sand. You can usually scoop that out yourself. A blocked road gully by the kerb is the municipality's responsibility; report it to them.

Doing it yourself: safely and sensibly

What you can do yourself

As long as you can work safely, there's plenty you can do. Start at the bottom: many downpipes have a leaf guard or access cover just above ground level, with a flap or a screw cap. Open it, take out the leaves and see whether there's water standing behind it. If the gutter can be reached from a low ladder, put on gloves, scoop out the leaves and clear the outlet. Then flush it through with the garden hose to check that the water runs away.

Why chemical drain unblockers won't help

A chemical drain unblocker is pointless in a downpipe. Leaves and moss barely dissolve in it, and whatever you pour into the pipe ends up in the soil, the water butt or local waterways. A harsh product can also damage a zinc pipe.

When to call us

Never work alone on a ladder, stand it on firm, level ground and don't climb onto the roof. Clearing a gutter on the second floor is not a job for a household stepladder. Call us as well if the blockage is underground, if the pipe stays full after you've opened the leaf guard, or if water is already running down the wall or getting inside.

Our approach to downpipe unblocking

When we unblock a downpipe, the engineer works from the top down, and from the bottom up if needed, starting by finding where the water is backing up. The gutter and outlet are cleared from the ladder; then a drain snake goes into the pipe through the access cover or from the bottom. It breaks up a plug of leaves or nesting material without damaging the pipe.

If the blockage is underground, a high-pressure hose comes next, flushing sand, silt and leaves all the way through to the sewer or the soakaway. If the problem keeps coming back, or we suspect a loose bend or roots, a camera inspection shows us what's happening in the underground pipe. If the problem turns out to be deeper in the sewer, sewer cleaning is the logical next step.

Finally, the engineer tests the whole system with plenty of water and gives you advice on leaf guards and maintenance.

What downpipe unblocking costs

We charge from €129 to unblock a downpipe. The call-out charge is extra and not included in that starting price; we'll tell you what it is beforehand. If the engineer comes out in the evening, at night, at the weekend or on a public holiday, we charge the out-of-hours rate.

If several downpipes and gutters need clearing, or a long underground pipe is blocked, ask for a quote. Here too, you'll get a price estimate over the phone first.

Keeping it from happening again

With a little maintenance, the drainage from your roof will stay clear for years:

• Clean the gutter at least once a year, after the leaves have fallen in autumn; if there are trees close by, twice is better.
• Fit a wire balloon guard in the outlet, so leaves stay in the gutter and don't wash down the pipe.
• Empty the leaf guard at the bottom of the pipe after every autumn storm.
• On a flat roof, check that the gravel guard is still sitting over the outlet.
• Keep a water butt diverter clean; its little filter silts up quickly.

Storm emergencies and our service area

A summer cloudburst or an autumn storm soon shows whether the drainage from your roof is up to the job. If water is running down the wall and getting inside, or standing on a flat roof, call 085 333 4698. We unblock downpipes in severe weather 24/7, and the engineer is usually with you within the hour. In the meantime, move belongings away from the wall and out from under any leaks.

We work in Arnhem, Tilburg, Hoofddorp and Amersfoort, among other places. The page about our service area lists more places with a city page of their own, and we cover the rest of the Netherlands too. Whether it's downpipe unblocking for a detached house or for a row of ten terraced houses, we always start with the same question: where is the water getting stuck?