I have 2 toilets on 2nd floor & 1 on 1st floor. All inside water levels go to maximum. On 2nd floor, one is a one piece low toilet – the other a two piece higher standard toilet.
Problem – both upper toilets begin flush, but don’t entirely empty tank so some residue remains – I’d call it a lazy flush. Using standard plunger doesn’t help. Toilet will empty if I add a pail of water as it’s flushing to bring the water to the top of the bowl. Then it will empty, so there isn’t a complete clog.
Could there be something wrong in soil drain pipe or stack? What can I do? Thanks.