I want to fill the toilet bowl with water as high as I can and let the water sit without draining for up to 24 hours. Why? To let some (gentle) cleansers do their work. I've tried shutting off the water at the wall and refilling the bowl from a pitcher, but inevitably the water starts draining too soon. Ideas?

  • The only think I can think of is Bernoulli. If it's windy outside, the wind over the top of the vent stack can create a Bernoulli effect and partially empty the toilet bowl. I cannot think of anything else that could cause the bowl to empty except a crack in the bowl itself, which would be pretty obvious.
    – BillDOe
    Nov 20, 2017 at 22:28
  • 5
    It drains because there's nothing actually holding it in - just the curve of the pipe which makes up the 'trap'. You'd have to physically block it somehow to keep the level above its normal 'finished flushing' level.
    – brhans
    Nov 20, 2017 at 22:43
  • 2
    Use a toilet plunger fit the plunger and fill if it is a good seal the bowl will stay full. I have had a young child flush a balloon that got stuck in the trap took a while to figure that one out, finally popped it with a drain auger but if the right size the balloon will make a good seal if the plunger won't seal tight.
    – Ed Beal
    Nov 20, 2017 at 22:59
  • Use gel cleaner and you won't have to keep the bowl filled.
    – bobflux
    Nov 5, 2020 at 13:25
  • Something like this: petersenproducts.com/…
    – Hot Licks
    Feb 13, 2023 at 4:52

10 Answers 10


The toilet bowl can only hold water as high as the top of the porcelain inside of chamber 5 in the picture below, unless you do something to stop it:

Toilet cutaway

  • 3
    Not sure why this answer has so many votes. It explains why the toilet flushes itself, but it doesn't answer the question of how to prevent the self-flush.
    – FreeMan
    Nov 5, 2020 at 12:29

Fill small plastic bag with one quart of water, remove excess air from bag and tie off. Place in toilet bowl. Dispose of bag when finished in trash receptacle.

  • 7
    I'd go further - secure a cord to the bag somehow, or use a very large bag not a small bag. Don't want it going down accidentally.
    – Criggie
    May 18, 2020 at 7:28

I know this is an old post but it seems to have a lot of recent views... so I hope by adding my experience it will help someone.

I use a heavy-duty (freezer or thicker) gallon ziploc bag and stuff a couple of wet microfiber kitchen towels or terry washcloths inside it, favoring one bottom corner to make a stuffed pointed bag. Then tie it shut with a string long enough to tie it off outside the toilet.

Shut the water off and flush to empty the tank, then empty the bowl with a fast bucket of water. Wedge the bag into the opening starting with the corner and shaping the bag as needed to fit (my Toto has a different shape than my American Standard).

This may take some time and effort to compress the cloths and achieve a proper seal. The bag will need to go in quite far, so tie it securely with no slack once it is in place. (I use enough wet towels in the bag to ensure the bag is a bit too large to go down easily, as added insurance. The force to flush it down will be very strong when you start to remove it.)

Seal any bottom jets the same way using wet terry washcloths and small freezer bags, also tied off outside the bowl.

Once the bottom openings are blocked, use a bucket to slowly and gently fill the toilet with the cleaning solution until it is full past the rim to the top edge. Do not rush this!

The water level holds overnight for me with little or usually no seepage.

To empty. Get a good grip on both bags and pull them away simultaneously and just enough to allow a small and steady stream of solution to release. The jet bag might pull away fully. Continue until the level has gone down enough to make the bags easy to pull away. Never pull just one bag (if using two).

Since the OP mentioned wanting to do this to have a cleaning solution soak, I want to mention an alternate method that doesn't require filling the bowl to the top.

I use an inexpensive submersible pond pump ($10-$15, 3-4 foot lift, low GPM) to circulate the solution from the bowl into the rim via the overflow tube.

Once a year, after plugging the bottom openings of the toilet as above, I run 1:1 bleach/water to kill any mold inside the rim for a couple of hours. After thoroughly rinsing away the bleach solution, I follow with a 10% citric acid solution (I've also used straight white vinegar) for a few hours to clear scale buildup. This annual maintenance keeps the toilets flushing and looking like new.

(In addition to following all electrical safety precautions when using the pond pump, I also plug the pump into an outdoor switchable outlet made for Christmas lights. It has a battery powered on/off remote control. I can operate the pump from anywhere, touchless. Safety first!)

  • 1
    This is a brilliant answer and I wish the OP would accept it. The idea of a cheap pond pump to recirculate cleaner is fantastic! Jan 25, 2023 at 23:04
  • Thanks! I use the pump annually on all the toilets. Acids and other cleaners will eventually ruin the pump (the cheap ones are not chemical resistant), but I usually get a few years out of one before it goes. IMO the ease of use is worth the cost.
    – Kat
    Jul 9, 2023 at 22:01

My solution was to sop up all the water first. I then used a balloon and filled it with some of that expanding foam. I gave it some time to harden creating a perfect fit for the opening. Washed it thoroughly & ready for subsequent uses

  • 1
    Nice - I like this idea :)
    – brhans
    Feb 12, 2023 at 22:28

Wad up a large trash bag and stuff it into the bowl, about as far as it will go. If it's not large enough, place a few crumpled paper towels into the bag and re-wad. It should be large enough to clog most toilets, it's easy to remove, and won't seep like a towel or rag would.

  • 2
    +1 but I will add that you need to be real careful that you don't flush that bag down when you fill the bowl with water, could make for a bad day. Nov 22, 2017 at 5:48
  • 1
    you can always tie the drawstings around the toilet rim to be sure ;)
    – dandavis
    Nov 22, 2017 at 6:46

I would try a child's balloon. You'll have to wedge it in tight so it doesn't float up. If you can't wedge it....try a water balloon.

In either case, with a string on the balloon tied to the flush handle or toilet seat.


Here's a completely different solution - to stop the water leaving, stop the air getting in. It will be fiddly but significantly reduces the risk of getting something stuck half way down.

  • Cut a sheet of heavy plastic sheet that fits tidily over the top of the open toilet.
  • Tape the edges all round smoothly and evenly with duct tape, leaving the front flapped back and having more tape ready.
  • Fill through the opening.
  • Flap down the front and tape.

If you can make it airtight the level will stay high indefinitely. More likely a tiny bit of air will get in but it will still hold for a few hours. Use clear plastic sheet and you'll be able to keep an eye on it. Untape carefully starting at the front, and you'll be able to stick it back down if the first treatment wasn't enough.

  • This is good, outside-the-box thinking! I've got to ask if you've tried this. I've poured water directly into the bowl, and it flushes pretty darn quickly. I'd imagine it would be difficult to fill the bowl then close & seal the flap before physics took over and emptied the bowl again. However, I'd be more than happy to be shown wrong on this one.
    – FreeMan
    Nov 5, 2020 at 12:31
  • @FreeMan I've done it with other things, and a toilet that was draining very slowly, to get cleaner soaking in the bend. Though a toilet drains faster than a sink, the flush allows fast (at least partial) filling. In fact filling using the flush will push air out so a small flap could be left shut but not taped right down. The key is to add the cleaner and any extra water both quickly and through a small gap. Taping around a funnel may also help. Funnels can be made to self seal by putting a floating ball (bigger than the outlet) in the bowl.
    – Chris H
    Nov 5, 2020 at 12:47
  • ... I'd consider experimenting, but I got rid of some bits of suitable sheet in this morning's rubbish collection and don't think I've got any more
    – Chris H
    Nov 5, 2020 at 12:48

I got it done but it is not as easy as one might think. Most of the time there remain some gaps water uses to drain out, and after a couple of minutes, water level is back to normal. So it is required to apply some kind of pressure all around the toilet bowl.

The best solution I have come up with involves using a garbage bag and a plunger.

  • Fill the garbage bag with water at 25% and stick it down the hole.
  • Put the plunger inside the bag so the bag adheres to the bowl, as depicted below.
    • If you press hard enough, it should be sealed tight enough.

Even with this technique, water level only holds for 1 or 2 hours, which is barely enough for cleansers to do their job.

bag and plunger


i hate to just plug a product but on tv flex tape looks like it may work. he literally takes a piece and pluggs up a above ground pool by taking a piece of the tape and literally plugging it from the inside of the pool. so the tape can get wet and still stick. enough pieces, im sure would make a perfect seal. and then just peel once done.

  • 1
    Seems overly complicated compared to the other solutions. The more joined pieces, the more places a leak can occur. And this has the risk-of-going-down-drain problem. It may be a fine produce (don't know) but this does not seem the right application for it.
    – keshlam
    Feb 13, 2023 at 0:13

I am in the process of doing my toilets. The following process worked perfectly for me: You will need 3-4 bread bags (for strength), fine sand, plumbers putty, string, 10 pound weight, vinegar, Zep Calcium, Lime, Rust remover.

  1. Create a sand bag with tripled up bread bags. Use enough sand to make the bag fit into the outflow, with enough to spread over the top of the outflow. (I filled 1/3 of the bag.) Tie off the bag near the top to create room to shape the bag into the toilet outflow.
  2. Create a ring from the plumbers putty and place on top of the toilet outflow. This servers as a gasket.
  3. Shape the sand bag into the toilet outflow.
  4. Place the weight on top of the sand bag.
  5. Fill the toilet with an appropriate mixture of vinegar and calcium, lime, rust remover.
  6. Periodically brush the toilet with a brush. I used a dish brush.
  7. Wait until rust, lime, calcium is loosened. It took a few hours or less for me. (I was not watching closely). Your results may vary
  • I hope this helps!

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