you have a restriction on your incoming water supply.the inlet water valve on toilet will need a strip down,this is needed to clear the obstruction that has come down through the supply pipeline.
wirecutterman, June 2012
Had the problem with my toilet cistern found muck blocking water flow, took valve out muck came out now filling good
Roger, May 2012
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I can answer this question...
my toilet cistern wont fill up quick enough after flushing?
