Vent, Valve & Volt
Toilet flush is weak or won't flush all the way

You can fix this

Likely cause: a chain that is too loose

With too much slack, the handle cannot lift the flapper far enough. Shorten the chain to a little slack.

Why this happens

Korky says that if the flapper chain is too loose, the flapper will not lift off the flush valve opening, causing a weak flush. HomeTips recommends about 1/2 inch of slack, and Korky recommends 1 to 2 links. Either way, the chain should be almost straight when the flapper is closed.

How to fix it

  1. Unhook the chain from the handle arm.
  2. Reattach it at a link that leaves 1 to 2 links of slack with the flapper closed.
  3. Flush and watch the flapper lift fully.
  4. Make sure the chain is not so tight that it holds the flapper open afterward.

If this does not fix it, tell the plumber

  • The flapper was barely lifting and you shortened the chain.
  • Whether the flush improved.

Build the full list: what to tell the plumber.

Start this troubleshooter over

References (every fact above comes from one of these pages)
  1. Korky: Slow or weak flushing toilet
  2. HomeTips: Toilet has a weak flush

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