Toilet Bowl Water Level Recedes & Drains Completely

The water surface area in the toilet bowl seats approximately five to seven inches from the toilet seat or rim, depending on the toilet brand. If that’s not where your water level sits, it could be dropping.

Bowl water can recede and even drain completely for two reasons, either there’s a blockage in the vent pipes causing a siphoning effect to the water in the bowl, or there’s a crack in the toilet bowl causing water to leak to the floor.

For both of these issues, there are quick and easy fixes you can try. Read as we expound on these issues further. Plus, there are great tips to help prevent slow loss of water in the toilet bowl.

Why the Toilet Bowl Water Level Recedes/Drops

The water level in the bowl could recede as a causal effect of water pressure in the bowl. If the water is entering into the bowl faster than water will naturally flow over the hump/ weir in the trap way, there will be a pressure difference.

As the water level is catching up, the pressure exerted on the water in the bowl will increase causing the water to pass over the hump and into the drain faster than it would, creating a siphoning effect. This is why the bowl water recedes and could empty the drain completely.

That, however, is only momentary, which is why the two most likely causes of water dropping and emptying the drain are either a crack in the toilet bowl or a clogged drain vent.

Since all the drains are connected to the sewer and the vent leading to the top of the house, any air drawn from the drainpipe is meant to release low pressure and break any air seals in the pipe.

If the vent is clogged, it has no way of drawing air leaving it to siphon the little air in the drainpipes. It can siphon the water in the toilet bowl, tubs, and sinks to draw air. This is why the water keeps receding.

A crack in the bowl, especially at the base is common. The only way to spot is is by checking for water at the surface of the toilet or the surrounding areas.

Water not Staying in Bowl, Drains Completely – What to Do

Listen for gurgling sounds in the toilet and the bathroom as well. This happens when the vent is clogged.

It will suck the air from the drainpipe causing a vacuum that gives off bubbling and gurgling sounds. The vacuum is probably also making the toilet bowl empty itself.

To stop this suction, you’ll have to clean the vents. Here’s how;

  1. Climb on the roof and locate the vent opening.
  2. Sweep up the opening to remove debris. If the vent is covered with a cap, use a screwdriver to remove it.
  3. Start by pouring water into the vent pipe using a spray hose. This should clear most of the waste. You may notice the pipe is starting to overflow with water.
  4. Feed a 20-foot auger into the vent opening and crank it up. Push till you reach a point of resistance. That should be the obstruction you’re looking for.
  5. Twist it around as you try to clear the clog. You should see the water begin to flow.
  6. Spray in some more water to check if it overflows again. If it doesn’t the vents are now clear.
  7. For deeper cleaning, put on some rubber gloves and use your hands to reach into the vent. Pull out whatever debris you find. It could be tree roots, leaves, branches, or anything else.
  8. Now head back down and check if there’s still some blockage in the toilet. If there is, plunge it close to the rear entry of the P-trap.
  9. The clog should be gone. Flush the toilet and check to see if the water keeps receding. You could then lay a rug on the floor and check in later to see if there are leaks.

If so, you should consider a crack in the toilet.

Toilet Bowl is Cracked

If there aren’t any clogs in the toilet, the next best guess is the cracked toilet bowl.

Cracked toilet bowl
Bowl with a crack

The toilet may be cracked practically anywhere, this makes it even harder to find it, but not impossible. Let’s first begin by trying to locate the crack to see if we can repair it.

  1. Drain water completely from the toilet using an absorbent sponge. As you do that, ensure no more water can get inside the toilet from the tank.
  2. Use a flashlight to look inside and outside the bowl trying to find the hole.
  3. If you spot a hairline crack at the side of the bowl and it doesn’t seem severe, move to repair the crack.
  4. Using a silicone waterproof sealant or the plumbers putty, apply the caulk while putting pressure to ensure it’s held securely.
  5. Leave it to dry for a few hours and flush the toilet to introduce water into the bowl. Check after some time if the water is still receding. If it is the crack could be at the base which means you have no other option but to replace the toilet.

Replacing the Toilet

Materials needed

  • New toilet
  • New tank bolts
  • Caulk
  • Adjustable wrench
  • Knife
  • Bucket and rag
  • Pliers

Method

  1. Empty the tank by flushing water and drain the remaining water in the bowl completely. This is to ensure no water interferes with the procedure.
  2. Use a rag to clean out water that may have spilled or is leaking from the bowl.
  3. If you have a one-piece toilet(toilet and tank attached), you have to remove the waterline and the tank.
  4. Unscrew the water hose that brings water to the tank then remove the mounting nuts that hold the tank to the toilet bowl. Lift the tank off.
  5. To remove the toilet, reach to the bottom of the toilet and locate the holding bolts. They should be on both sides.
  6. Unwound the nuts using an adjustable wrench and lift the toilet. Use a knife to scrape off the caulk that was holding it down. Clean up the area with a rag.
  7. Align the new toilet and screw in the bolts to the floor. Tighten its grip with a wrench or a pair of pliers.
  8. Don’t forget to add in a new wax seal and attach the toilet flange securely or you’ll be looking at another source of leaks.
  9. Apply caulk at the base of the toilet to prevent the seat from wobbling.
  10. Reattach the tank or if you bought a one-piece you’re done. For the tank, screw and tighten the bolts underneath the tank.
  11. Reconnect the water supply and use the toilet to see if it’s working fine.

Tips to Prevent Slow Loss of Water from the Toilet Bowl

  • Fix every clog in the toilet as soon as it occurs.
  • Regularly clean the vent pipe and ensure it’s free from dirt, debris, and trees.
  • Inspect the toilet for cracks once you suspect there may be one.
  • Fix other toilet issues such as unstable toilet base, as soon as you notice it.

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