Over 30 years ago I plumbed in my first power shower – thankfully not the first of many. It was over a freestanding original Victorian cast iron bath (complete with lion’s feet) in the middle of a bathroom that was as big as my sitting room. It was the most powerful shower pump on the market at that time (at 3 bar) and, combined with a nine inch shower rose was sized to deliver 20 litres of water a minute. It was a thing to behold – especially given the showers I was used to installing back then.
Installation completed I turned on the shower to check that everything was working perfectly. For about three minutes, whilst checking for leaks I marvelled at the stream of water emitting from the shower head noting that the noise of the water drowned out the noise of the pump. And then… nothing. No water at all! As it was obviously an electrical fault or catastrophic pump failure, I called over the electrician who fiddled around for about 45 minutes before declaring that he couldn’t find anything wrong. In the words of Right said Fred, “We were getting nowhere. So Charlie and me ‘ad another cup of tea and then we went ‘ome…”
The next day it was working perfectly again for another three minutes… Eventually we realised that the fault wasn’t with the pump at all. The dry-run protection mechanism was cutting in because the mains could not refill the cold water storage and feed cistern (or “tank in the loft” as the non-plumbers amongst you may call it) fast enough, so it was being completely drained. And the moral of the story? Well, you would hope that it would have been to get a smaller pump, but of course it wasn’t. It was to upgrade the mains, and increase the size of the storage cistern to 150 gallons (670 litres) capacity! (Unvented cylinders weren’t an option then)
Nowadays a shower pump at 3 bar is quite tame (see size doesn’t matter) and 30 litres/minute is easily achievable (combined with a specially designed shower tray to ensure the bathroom floor doesn’t flood!).
So what does a shower of 30 litres/minute mean across a whole year? Assuming a 5 minute shower (calculated by the Government as the UK average) then it would require 150 litres of water compared to 35 litres under a shower like mine. Over the course of a year, showering every day, would result in an extra 41,975 litres of water. In a more alarming, but quite likely scenario of a 10 minute shower a day (after all, why upgrade to such a high spec shower unless you felt that it is all about the showering experience rather than just getting clean), the extra water required for just one person’s shower, becomes 83,950 litres.
That amount of water would provide all the water requirements for a year for 1.5 ‘average water users’. Or, 3.3 Caths (the new unit of measurement in the water field; like ”the size of Wales” only more egotistical).