No rain in Hampshire and looks like we'll be missing more of these 'months in a day' deluges too so finally bit the bullet and had to buy a RO unit as my butts were down to the last couple of watering cans! Thought I'd post a few observations if anybody else is in the same situation
How do you pick a system to buy? I went for the Amazon sold compact RO 4-stage unit from Vyair - seemed a reasonable price (£48) and had good reviews (and I had some credit with Amazon). It came two days later and plumbed up today (temp set-up to test and see how it worked):
Set-up easy - most of it was already pre-plumbed. Just had to add the DI resin, RO filter, and run a few litres to clear etc. Instructions to do all this were fairly clear. Currently its just on the outside tap at the back of the house which is fed from the header cold tank so far from ideal.
Now tap water around here is as hard as nails. Cold water readings are in the high 300s (take this as +/- 10 or 20 ppm):
Already have a Pozzani two-stage filter but this only reduces the TDS to around 240 ppm (for comparison a Samsung fridge filter only reduces the TDS by about 50 ppm or less) so not really an option for the CPs!
Taking readings from my water butts the stuff from my house roof (concrete tiles) is around 45 ppm and that collected off my greenhouse roof around 15 ppm (both of these +/- 5 ppm). This therefore gives me something to aim for as I've never had any problems with using either of these sources for my plants.
Pre-DI readings from the RO filter showed water at the 80 ppm level (the 'red' pipe water water was over 500 ppm) which seemed a little disappointing! Once the DI stage was introduced I got a reading of:
Can't say I'm unhappy with this
Its slow with this water pressure and so will look at plumbing into the rising main to get full mains pressure and see if that helps but over a few hours today I've got about a third of a water butt of good water now. How long the filters and RO last is the big question. I can see the DI changing colour already so will re-test the ppm tomorrow when I re-start and see how its going. I guess with 80 ppm hitting the DI resin I'm going to go through a fair bit of that to keep it so low but that's the cheap bit. Initial ppm being so high may mean a fairly short life on the RO membrane filter too.
If only it would rain