How to Drain a Toilet: Empty the Cistern and the Pan
Step-by-step guide to draining a toilet before a repair or replacement: shut off the water, empty the cistern, get the water out of the pan and trap, and avoid a mess on the floor.
To drain a toilet, turn off the water at the isolation valve on the cistern's supply pipe, or at the stopcock, then flush and hold the handle down to empty the cistern. Sponge out what's left. For the pan, bail out the water with a small cup, then use a plunger or a sponge to push or soak up the water sitting in the trap. You only need to empty the pan if you're lifting the toilet or working on the pan itself.
Key Takeaways
- Shut off the water first, then flush. A cistern won't empty if it's still refilling.
- A few centimetres of water always stay in the bottom of the cistern. Sponge it out before undoing anything underneath.
- You only need to empty the pan if you're removing the toilet or working on the pan connector.
- Bail the pan with a cup, then force the last of the trap water down with a plunger, or soak it up with a sponge.
- Never pour drain chemicals into a toilet you're about to dismantle.
To drain a toilet, turn off the water supply to the cistern, flush and hold the handle down, then sponge out the water left in the bottom. If you also need the pan empty, bail it out with a small cup and push the last of the water through the trap with a plunger, or soak it up with a sponge. The whole job takes about 15 minutes and needs nothing more than a bucket, a sponge and some old towels. Below is each step, plus what to do if the cistern won't empty or the toilet is a concealed or macerator type.
When you need to drain a toilet
Draining the cistern is the first step for most toilet repairs: replacing a fill valve or flush valve, fixing a leak where the cistern bolts through to the pan, or swapping a flush button mechanism. Draining the pan as well is only needed if you're lifting the toilet, replacing the pan connector, or fixing a toilet leaking at the base.
If the toilet is blocked, don't drain it and start dismantling. Clear the blockage first. Our guide on how to unblock a toilet covers what to try.
What you need
- A flat screwdriver for the isolation valve
- A bucket and a small cup or jug
- A large sponge, and rubber gloves
- Old towels to lay around the base of the toilet
- A plunger, if you're emptying the pan
- A wet and dry vacuum, if you have one. It makes the job quicker.
How to drain the cistern
Turn off the water
Find the isolation valve on the pipe feeding the cistern and turn the slot a quarter turn so it sits across the pipe. Our guide to the toilet isolation valve shows where to find it and what to do if it won't turn. If there's no valve, turn the water off at the stopcock.
Flush and hold
Take off the cistern lid and put it somewhere safe, as ceramic lids break easily. Flush and hold the handle or button down so the flush valve stays open as long as possible.
Check it isn't refilling
Watch the fill valve. If water is still coming in, the isolation valve isn't sealing. Turn the water off at the stopcock instead.
Sponge out the rest
There's always a few centimetres of water below the flush valve. Soak it up with the sponge and wring it into the bucket until the cistern is dry. This is the water that ends up on the floor if you skip this step and undo a nut underneath.
How to drain the pan
Lay towels around the base
Pan water is dirty water. Put towels down and wear gloves.
Bail it out
Scoop the water out of the bowl with a small cup into the bucket until you can't get any more.
Clear the trap
Some water always stays in the trap, the bend at the bottom of the pan. Push a plunger firmly into the outlet a few times to force it down the soil pipe. Alternatively, keep pushing a sponge into the outlet and wringing it out.
Dry the last of it
Push an old towel into the outlet to catch any drips. If you're lifting the pan, keep it upright as you move it, as a little water will still be sitting in the bend.
Once the pan is off, stuff a rag into the soil pipe to stop sewer gas getting into the room, and remember to take it out before you refit anything.
Concealed, macerator and old high-level toilets
Concealed cisterns. The isolation valve and the flush valve are inside the wall frame. Take off the flush plate, turn the water off through the opening, then flush. You usually can't sponge out the last water through the plate hole, so a wet vac helps. See concealed cisterns for how the access works.
Macerator toilets. Switch the unit off at the fused spur before touching anything, then drain the cistern in the normal way. Water also sits inside the macerator unit, so draining the pan fully is a different job. If a macerator is the problem, read macerator toilet problems before you start.
High-level cisterns. Older London homes sometimes have a cistern high on the wall with a pull chain, often fed from a tank in the loft. The valve may be on the pipe near the cistern or at the tank. Draining it is the same idea, but you'll need a step ladder and a steady hand with the sponge.
Common problems
| Problem | Likely cause | What to do |
|---|---|---|
| Cistern keeps refilling | Isolation valve not sealing | Turn off at the stopcock |
| Flush doesn't empty the cistern | Faulty flush valve or button linkage | Sponge or vacuum the water out |
| Isolation valve won't turn | Scale around the spindle | Don't force it. Use the stopcock |
| Pan water won't go down | Partial blockage in the trap or soil pipe | Clear the blockage before dismantling |
| Water on the floor after refitting | Cistern washer, pan connector or supply joint | Dry everything and flush to find the drip |
When to call a plumber
Draining a toilet is straightforward. The trickier part is usually the repair that follows. Call a plumber if the water won't turn off properly, if the cistern-to-pan bolts are seized or corroded, if the pan is cracked, or if the toilet is concealed and you can't get at the valves. A leak that returns after refitting often comes from a pan connector that isn't seated properly, and it can soak a floor before you notice it.
We handle toilet repairs, cistern repairs and full toilet replacement across London. Our labour is £95 an hour, the £60 call-out is waived when the job runs over 2 hours, and we confirm the price before any work starts.
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Frequently Asked Questions
How do you drain a toilet cistern?
Turn off the water at the isolation valve on the supply pipe or at the stopcock. Flush and hold the handle or button down so as much water as possible runs out. Then sponge out the water left in the bottom of the cistern and wring it into a bucket.
How do you get all the water out of a toilet pan?
With the water off, bail out as much as you can with a small cup or jug. Then push the plunger firmly into the outlet a few times to force the water in the trap down the soil pipe, and soak up any that's left with a sponge or old towel.
Do I need to drain the toilet to replace the fill valve?
You need to empty the cistern, but not the pan. Turn off the water, flush, and sponge out the cistern before undoing the supply and the valve nut underneath. The pan only needs draining if you're lifting the toilet or changing the pan connector.
Why won't my toilet cistern empty when I flush?
Usually because the water is still on and the cistern is refilling, or because the isolation valve isn't sealing. Check the valve is fully closed, across the pipe. If the cistern still fills, turn off the stopcock. If the flush itself doesn't work, the flush valve or button linkage may be faulty.
Can I use a wet vac to drain a toilet?
Yes, a wet and dry vacuum is quick for both the cistern and the pan, as long as it is rated for liquids. Empty and clean it straight afterwards. Don't use an ordinary household vacuum.