Only go for the Merlin if you have good pressure. They run best at 70 to 80psi, but even at this pressure they will only acheive a maximum reduction in tds of 90%, which will mean using lots of de-min resin.
WARNING: The GPD rating of membranes is in US gallons (smaller than a UK gallon) also these rates a calculated with a water temp 25'C, on UK mains supply of about 5'C you can expext a reduct in production of abot 50%. And then there's the pressure, rates are usually quoted at 70 to 100psi.
Dont buy an RO just because the maker says it will make x thousand gallons a day, ask question, ask for references, ask for the names of other users. And don't buy it because its cheap, the only reason its cheap is because its cheap.
