Fernox LSX and Plumbers mait (BUY ON AMAZON) are the two best sealant for bath waste to try today.
A bath waste typically wouldn’t need anything other than the thin washer that goes between the waste and the inside of the bath and the thicker one that goes between the bath underside and the nut that fixes everything together.
Sometimes this fails to seal depending on your bath type and the simplest fix would be to use a silicon between the thick washer and the underside of the bath (double-check to make sure every part is dry) and leave it to cure after tightening up before using it.
The reason WE DO NOT RECOMMEND SILICONE SEALANT is that they ted to leak in time as they’re generally not designed for this type of use. Much better options include Fernox LSX and Plumbers mait.
Best Sealant for Bath Waste
Fernox LS-X External Leak Sealer and Jointing Compound, Yellow
I first tried using this to fix a hot water boiler tank in a mobile home and it did wonders. Over the years, I continue to recommend this product for almost every application and guess what? It has never failed me or my customers.
It seals punctures in inflatable ring of inter self-riser swimming pool, fixes underwater seal leaks, punctures and cracks whilst pools, radiators, tanks, and the likes are still in use.
Without a doubt, this remains the best leak sealer on the market. If you doubt, check out the massive reviews on the internet (especially on Amazon), and after 27 years of use, it’s never let me down, it’s the same formula today as it was then, and that’s because you can’t improve upon perfection.
Evo-stik Plumbers Mait, 750g
This sealer works on almost every situation I have tried it in – bath waste, drainage pipes, washers, cupboard, sinks, etc. It comes highly recommended.