BBC News has reported that Thomas Dudley Ltd, one of the UK’s largest plumbing manufacturers, has a testing station that puts any new mechanism through its paces with 200,000 constantly repeated flushes, taking four months.

Managing director Jason Parker says: “A siphon will not leak whereas an outlet valve – if we look at the figures we’ve got – they could leak within a week of installation. It could be two years but they will leak.”

Siphons are now being made dual flush, so he wants drop valves outlawed despite the fact they are his biggest seller and such a move could harm his business.

“If we’re serious about wasting water and we want to stop it, the only way to do that is put a siphon back in,” he says.

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