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How to Unblock Drains Outside
The gully by the back door is standing full, or the chamber in the back court has water sitting in it that will not drop. This is the outside version of the job, and it is a different piece of work from a slow sink indoors. Bigger pipe, different tools, and one observation at the start that decides everything after it.
The Short Answer
Lift the cover before you touch anything. A chamber standing full means the blockage is downstream of it, so rod towards the sewer. A chamber that is empty while the house backs up means the blockage is between the chamber and the building, so rod the other way. Get that right and most outside blockages come out with a plunger head and three or four rods in twenty minutes. Get it wrong and you will spend an afternoon rodding clear pipe.
Gully or Chamber: Two Different Problems
Outside drainage on a typical Glasgow property has two things you can open. The gully is the small open drain with a grid over it, usually at the base of a rainwater downpipe or just outside the back door, and it takes waste water from the kitchen and bathroom. The inspection chamber is the bigger cover, round or rectangular, sitting over the point where runs join or change direction, and it gives you access to the main pipe.
They fail differently and it is handy to know which one you are looking at. A gully clogs at its own trap, with grit off the roof, leaves, moss, cooking fat and hair coming down the waste. That is a hand and a trowel job and no rods are needed. A chamber holds water because the run leaving it is obstructed, and that is a rodding job.
The tell is simple. If the gully is full but the chamber beyond it is empty and clean, the blockage is in or just after the gully trap. If both are full, you are past the gully and into the main run. And if the chamber is bone dry while the house is backing up, the blockage is upstream of the chamber, between it and the building, which surprises people because everything outside looks fine.
Clearing the Gully Trap by Hand
This is the job that fixes an outside drain more often than anything else, and there is genuinely nothing to it beyond a willingness to put your hand somewhere unpleasant. Heavy duty gloves, a bucket, and a small trowel or an old serving spoon.
- Lift the grid. Most lift straight out. Some are bolted down with two screws that will be seized, in which case penetrating oil and ten minutes of patience beats brute force, because snapping a bolt off in a cast surround turns this into a much longer job.
- Scoop out the standing debris first, before you reach for the trap itself. Leaves, silt, grit, moss. Into the bucket, not down the drain, which is where a lot of it came from.
- Reach into the trap. There is a U bend in the bottom exactly like the one under a sink, and it holds water to stop smells coming back up. Feel around the bend and pull out what is in there.
- Flush it hard with a hose and watch. Clear water disappearing immediately means you are done. Water that pools and drains slowly means there is more further along.
- Put the grid back. An open gully is a hazard and it is an open invitation for the next lot of leaves.
Rodding an Outside Run
If the chamber is holding water, this is the part that clears it. A set of drain rods is around twenty five pounds and pays for itself the first time. The heads screw on: a plunger head for general work, a corkscrew head for fibrous material and roots, a scraper for silt.
The one rule that matters, and it is worth repeating because getting it wrong is expensive: turn clockwise, always, and never let the rods turn the other way while they are in the pipe. The sections screw together clockwise, so an anticlockwise turn unscrews them underground and leaves you with a drain blocked by both the original obstruction and your own rods. Retrieving them means excavating, and that is not a twenty five pound afternoon any more.
Push steadily rather than ramming. You are feeling for the difference between the rod head meeting the far wall at a bend, which is soft and stops dead, and meeting a blockage, which gives slightly and then resists. Add rods one at a time so you always know roughly how far in you are, because that tells you where the problem sits if you end up needing someone with a camera.
Once it gives, do not stop. Rod past it, then work the head back and forth a few times to break the material up, then run a hose or the kitchen taps hard for two or three minutes to carry the debris away rather than leaving it to settle twenty feet further on and block again next month.
When Rodding Will Not Fix It
Rods are a blunt instrument and they are excellent at what they do, which is punching a hole through a soft obstruction. There are three situations where they will not get you there and it is better to know early.
Heavy root ingress is the first. Rods will clear a channel through a root mass and the drain will run again for a while, and then it will not, because the roots are still in the pipe and still growing. Clearing roots properly means cutting them out under high pressure jetting, and then dealing with the crack that let them in, or they simply come back.
A dip in the run is the second, and rods are actively misleading here: they pass straight through and meet no resistance, so you finish convinced the drain is clear while the standing water that caused the problem is untouched. There is nothing to clear, only a shape of pipe. The tell is that the drain runs freely after rodding and is slow again within a fortnight.
Compacted silt and building debris is the third. Sand, plaster and cement washed into a drain during work set into something rods will polish rather than remove. Jetting shifts it. Rodding mostly does not, and if you have had an extension or a bathroom done in the last year and the drains have been odd since, that is very likely what happened.
While You Have the Cover Off
You are already there and already mucky, so spend two more minutes gathering information. Almost nobody does this and it is the difference between a useful phone call later and a shrug. Take a photo on your phone of the open chamber, with the flow visible if you can manage it. A picture from before the first clearance is worth a great deal if the same drain plays up again in six months, and no customer has ever had one.
Look at what the pipe is telling you while the water is moving. A tide line of silt part way up the channel shows where water habitually stands, which means the fall is wrong or something downstream is holding it back. An open or stepped joint where two lengths meet is where material catches. Anything growing through is self explanatory. None of that needs interpreting on the spot, it just needs recording.
Count your rods and write the number down. If you used four rods before you met the blockage, that is roughly a twelve foot run from the chamber, and it puts whoever comes next straight to the right stretch of pipe instead of starting from nothing. It is the single most useful thing a customer can tell us on the phone and it costs you nothing but the noticing.
What the Weather Does to a Glasgow Gully
Rainfall is the thing that makes outside drainage here behave differently from indoor plumbing, and it is the single most useful piece of context for this particular job. A good deal of the older city drains on a combined system, where the same pipe carries foul waste and everything coming off the roof. That means a run with a partial restriction copes perfectly well on an ordinary day and surcharges the moment a downpour adds the whole roof area to it.
So the timing of the problem is diagnostic, and it is worth paying attention to before you phone anyone. A gully that backs up only during heavy rain and clears an hour later is telling you about capacity or a partial obstruction well downstream. A gully that is full on a dry Tuesday is telling you about a blockage close by. Those are different jobs, and rodding the first one on a dry afternoon will find nothing wrong at all, which is a wasted visit for everybody.
Autumn is the other pattern, and it is predictable enough to get ahead of. The mature street trees through the West End and along the Southside avenues drop enough leaf to blind a gully grid in a couple of wet weeks, and a blinded grid sends the water over the top rather than down. Most of the calls we get in October and November are not blockages at all, they are grids that needed brushing off. Two minutes with a stiff brush in late September saves a lot of those.
Then there is what the buildings themselves shed. Sandstone tenements give off a fine grit and mortar dust that washes down with the rain and settles in the bottom of a gully trap, and unlike leaves it does not float or wash through, it compacts. That is why a gully that has never been emptied can be almost solid while the pipe below it is perfectly clear. Scooping the trap out is the whole fix in those cases, and it is the first thing to try before anyone reaches for rods.
When to Call Someone Out
Call when the chamber is full and rodding has not moved it, when more than one property in the close is affected, or when foul water is coming back up rather than going away. That last one is urgent and blocked drains runs 24/7 for exactly that reason. Also worth calling rather than persevering if the drain has blocked in the same spot more than twice, because the third clearance is money spent on a symptom and half an hour of camera time answers it properly. Kyle runs the jetting side, and a jet will strip compacted grit and root material off the pipe wall where rods only bore a hole through the middle of it and leave the rest sitting there. That difference is usually why a drain that was rodded clear last month is blocked again this month.
Blocked Drains in GlasgowCommon Questions
Open the inspection chamber and look at the water level. Standing full means the obstruction is downstream, between that chamber and the sewer, so you rod away from the house. Empty and dry while sinks and toilets inside are backing up means the obstruction is upstream, between the chamber and the building. Reading the chamber first is the difference between twenty minutes and an afternoon.
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