Our bathroom has had a double trap syphonic loo for many years and now
it's time to re-fit the bathroom.

We've always apperciated the fact that it's very quiet in operation and
that it clears waste at the first attempt every time. We often notice
that when visiting other houses, modern loos don't always succeed in
properly emtying first time, or even after a second flush.

Naturally we would prefer to replace it with a similar one, but our
local bathroom centre told me that they use too much water and are no
longer allowed in the UK.

Is this true ?

is there any way of finding out before you install it, just how
efficient a particular loo might be at clearing waste ?