The signs, and what each one points to
Start by noticing which outlets are affected, because that tells you where the blockage sits.
One slow outlet on its own, such as a basin or a shower, almost always means the blockage is in that fitting's own trap or waste pipe, within a metre or two of the plughole. That is the easiest kind to clear.
Several outlets slowing at once is different. If the bath, basin and toilet upstairs all drain sluggishly, or water rises in the shower tray when the toilet is flushed, the shared pipe they all feed into is struggling. That pipe usually runs down the outside wall or inside a boxed-in stack and then into the underground drain.
A bad smell outside, water pooling around a gully, or an inspection cover in the garden that is full to the brim all point to a blockage in the underground run itself.
What usually causes it
Inside the house, hair and soap are the classic culprits in bathroom wastes. They bind together into a mat that catches everything else. In kitchens it is fat and food scraps: fat poured down hot sets hard further along the pipe, where it cools.
Toilets block when something goes down that should not. Wet wipes are the biggest single cause, even the ones sold as flushable, along with cotton buds, sanitary products and too much paper at once.
Outside, older clay drains can be pushed out of line by ground movement or tree roots, leaving a lip that catches waste. Leaves and silt wash into open gullies. These are not problems you can reach from indoors.
What you can safely try yourself
For a single slow basin, bath or shower, try these in order.
First, pull out whatever you can see. Many shower and basin wastes have a removable cover or pop-up plug with a clump of hair wrapped underneath.
Second, use a plunger. Block the overflow hole with a damp cloth so the pressure goes down the pipe rather than out of the overflow, then plunge firmly for half a minute.
Third, for a basin, put a bowl underneath and unscrew the trap, the U-shaped section directly under the plughole. Clean it out, check the washers are seated and screw it back hand-tight.
For a toilet, use a proper toilet plunger with a flange rather than a flat sink plunger, and stop flushing if the water is rising. Repeated flushing on a blocked pan is how bathroom floors get flooded.
If you lift a garden inspection cover, do it carefully, keep children and pets away and put it back securely.
What not to do
Avoid pouring strong chemical drain cleaners into plastic wastes over and over. They can soften seals and joints, and if the blockage does not clear you are left with a pipe full of caustic liquid that someone has to open up.
Do not keep using a toilet, bath or shower that is backing up while you wait. Every litre adds to the pressure on the blockage and to the risk of an overflow.
Do not push drain rods into a pipe you cannot see the end of if you are unsure what you are doing. It is easy to lose a rod or damage an old clay joint.
When to stop and call someone
Call when the plunger and the trap have not helped, when more than one outlet is affected, when water comes up where it should not, or when the blockage keeps coming back every few weeks. A recurring blockage nearly always has a cause further down the line, and clearing the symptom each time costs more in the long run than finding it once.
If waste water is coming up into the house, stop using the water in that part of the house and keep people away from it. Our hours are Monday to Friday, 8am to 6pm. For urgent jobs during those hours we try for the same or next working day and give you an honest timing on the phone first.
What a visit from us involves
When you call or send photos, tell us which outlets are slow, whether the toilet is affected and whether you have an inspection cover outside. That lets us arrive with the right kit.
On the day we work out where the blockage is before doing anything else, then explain what has caused it and what it will take to clear. You get the price before work starts. We do not add urgency surcharges.
We clear the blockage, run water through every affected outlet to prove it is flowing freely, reseat any traps or wastes we have opened and leave the area clean. If we find a damaged waste, a failed seal or a leak while we are there, we tell you and price the repair separately so you can decide.
From our Gloucester base, we serve Gloucester, Cheltenham, Tewkesbury, Stroud, Malvern, Ledbury, Newent and Ross-on-Wye. If you are outside that area, the safe steps above still apply and a local drainage firm is the right call.