Blocked or Slow Shower Drain: Clear It Without Chemicals

Why is my shower draining slowly?

Work out which of these fits before you start, because the fix is different for each. The first one accounts for most slow showers, and you can clear it yourself in ten minutes with a pair of rubber gloves.

• Hair and soap in the trap. The drain slowed down over weeks, the water clears eventually, and nothing else in the bathroom is affected.
• Hard scale on top of the scum. Common with London’s hard water: the gunk in the trap is grey and gritty rather than slimy, and it will not wipe off.
• A blockage further along the waste pipe. The trap looks clean when you open it, but the water still backs up.
• A shared pipe or stack. The basin or bath next to the shower gurgles when the shower runs, or the toilet level rises and falls.
• A poor fall on the waste pipe. The shower has drained slowly since the day it was fitted, often on a low tray or a wet room floor.

How do I unblock a shower drain without chemicals?

Go through these steps in order and test the drain with the shower running after each one. Stop as soon as the water clears freely.

• Take the cover off. Most chrome domes pop off or undo with one central screw. Wet room grates lift out with a small hook or a flat screwdriver.
• Pull out what you can see with gloved fingers or a cheap plastic barbed drain strip. Most of the blockage usually comes out as one long mat of hair.
• Lift out the removable part of the trap: a cup, a dip tube or a plastic insert, depending on the type. Scrub it in the basin with washing-up liquid and an old toothbrush.
• Scrape the inside of the trap body where you can reach it, then refit the insert firmly. A loose insert lets drain smells into the room.
• Run hot tap water with a good squeeze of washing-up liquid for a couple of minutes to shift soap film further down.
• If it is still slow, use a small sink plunger over the outlet with a few centimetres of water in the tray. If the shower shares a waste with a bath or basin, hold a wet cloth over that plughole so the push goes down the pipe, not out of the other fitting. Short, firm strokes work better than long ones.
• The last DIY step is a hand drain auger fed through the trap body. Go gently: a thin plastic trap can crack if you force the cable round its bend.

Skip caustic drain cleaners. If they do not clear the pipe you are left with a tray of corrosive water that splashes when anyone opens the trap, and repeated use is hard on plastic seals. Use hot tap water rather than a boiling kettle on acrylic trays and push-fit waste joints.

Shower fully blocked with water standing in the tray?

When the tray holds water and nothing goes down, the first job is to get the water out so you can see what you are doing. Scoop it into a bucket with a jug, then soak up the last centimetre with an old towel or sponge. Plunging or poking through a full tray only splashes dirty water over the floor and the seals.

Then take the trap apart as far as it is designed to come apart from above. On most tray wastes that means lifting the cover, undoing the centre screw or unclipping the cup, and pulling out the dip tube or insert. Leave the large threaded ring around the outlet alone: it clamps the waste body to the tray, and loosening it breaks the seal underneath, which is how a blocked shower turns into a ceiling leak. With the insert out, look down the throat of the trap body. A bottle brush or a bent piece of stiff wire pulls out the hair packed below where fingers reach. Wash the insert, refit it, and run the shower to test.

If the throat is clear and the tray still fills, the blockage is past the trap. Try the plunger now, with a little water back in the tray and any shared plughole covered. If that fails, what happens elsewhere tells you whose problem it is:

• Nothing else in the home is affected: the blockage is in the shower waste pipe, which is yours to clear. A hand auger may reach it; a long run under a tray usually needs a plumber with a drain machine.
• The bath or basin on the same branch fills or bubbles too: the shared waste inside your home is blocked. It is still your pipework, and clearing it is usually quicker from an access point on the branch than through the shower.
• The toilet rises or empties slowly as well, or dirty water appears in the tray when you flush: the soil stack or the drain below is blocked. Stop using water in the house until it is cleared, as described in toilet blocked and water rising.
• In a flat, water comes up when a neighbour runs theirs: the shared stack is blocked. That is normally for the freeholder or managing agent to arrange, not something to rod from inside your shower.

Which shower trap do you have?

The trap is the short U-shaped or cup-shaped section that keeps a plug of water between your bathroom and the drain. Under the building regulations guidance for England (Approved Document H), a shower trap should be 40mm with a 50mm water seal. The seal can drop to 38mm only where the shower discharges straight to a gully. The same guidance says a trap should be removable or fitted with a cleaning eye, so there should always be a way in.

Most showers in London homes use one of four types, and knowing yours saves you prising at the wrong part:

• Standard tray waste: a round chrome cover over a trap body with a removable cup or dip tube. Hair wraps round the tube and the cup fills with sludge.
• Low-profile or shallow-seal trap: fitted under low trays where there is little depth. The water seal is small and the passages are tight, so it blocks sooner, and a long pipe run can siphon it dry and let drain smells in.
• Linear or wet room drain: a long channel with a lift-out grate and a trap insert, often with a hair tray. The channel itself collects scum along its full length and needs brushing out.
• Waterless valve: a flexible membrane in place of water. Hair caught in the membrane holds it open, which causes both slow draining and smells.

If the trap is sealed under a tiled-in tray with no access panel, do not cut tiles to reach it. A plumber can usually work through the outlet from above.

The trap is clean but it still drains slowly: is it the stack?

Once the trap is clear, the next place to look is where the shower waste joins other pipes. Run the shower hard for a minute and listen. If the bath or basin plughole bubbles, the shared branch pipe between them and the stack is partly blocked. If the toilet water rises or gurgles too, the blockage is in the soil stack or the drain below it.

On a ground floor, lift the cover of the outside inspection chamber if you can do so safely. A chamber full of standing water points to the drain rather than your shower, and depending on where the blockage sits it may be the water company’s job. See who deals with a blocked drain before paying anyone.

In a flat, the stack is often shared with the flats above. Water or scum coming up through your shower tray when a neighbour empties a bath is a stack blockage, and the freeholder or managing agent usually arranges it. Our guide to a plumbing emergency in a block of flats covers who to call first.

Gurgling on its own, with the trap emptying and a drain smell afterwards, can mean the stack is not venting. An air admittance valve on the top of an internal stack can stick shut. That is a quick part swap, but it needs the right access. If the smell is the main complaint, see why a shower drain smells.

What a plumber does and what it costs

On a slow shower the engineer starts at the trap, the same as you did, then works outwards. That usually means taking the trap body apart, feeding a drain machine or long auger along the branch pipe, and finding the point where the cable stops. Where a pipe has sagged or was laid with too little fall, the proper fix is to relay that section, which can mean lifting the tray.

If the fault is shared, such as a stack or an outside drain, the plumber will tell you rather than rod blind for an hour. When the toilet is affected too, the job is the same one described on our blocked toilet service page. For our own terms, you pay the £60 call-out, and the repair price is agreed with you on site before any work starts. See how plumbers quote for what to ask before you agree a price with anyone.

How do I stop it happening again?

A hair catcher that sits on the grate is the single biggest help, especially in households with long hair. Empty it after each shower rather than rinsing it into the drain. Lift the cover and wash the trap insert once a month, which takes five minutes and is far easier than clearing a solid mat.

Do not ignore a tray that holds water for a long time after every shower. Standing water finds its way through tired silicone and grout, and the first sign is usually a stain on the ceiling below. If that has already started, read what to do about a ceiling leak below a bathroom and check the seals around the tray for a leaking shower.