Up to now never had a water meter
new place has one fitted it
west sussex very hard area
traditionally use around 400 / 500 litres / day
what would be a good set up looking for something compact and economical
Not to expensive either
Pressures seems a bit better here but would a booster benefit
maybe a merlin or would waste be a issue
With the hardness we suffer down here, resin is going to cost you a mint, so I suspect an RO is called for.
A booster will definitely improve your rejection rate but what you're looking for is to minimise the waste ratio. That's purely a matter of how much waste you allow when you set your waste valve.
You can reduce the waste ratio as far as you like but it'll be at the cost of a shorter membrane life. However, with water at the price it is, you'll almost certainly be better off minimising your waste even if you need to buy more membranes.
One thing you can do is to call your water supplier (which I guess would be Southern Water - 0845 278 0845) and get them to send you a non return to sewer form. Fill it in in the day you receive it, as they won't backdate claims. What it does is reflect the fact that you're not using the sewers to dispose of the waste from a RO unit. That's as simple as making sure that the waste runs into your garden rather than down a drain (they may inspect to check).
Southern Water are astoundingly amateurish about this; they just seem to want to deal with your estimate, but the franchisees all have meters on their pipes, so we're hoping to get an accurate number at the end of the year.
Is it worth getting a non return to sewer form? Well, Southern Water's charges are currently £1.20 for water coming in and £2.27 for water going down the sewer, so you'll save around 2/3 of your water costs by getting one. The hassle is definitely worth it. Using your numbers and a 1:2 pure:waste ratio, you'll be running 1.5m
3 every day that isn't ending up in the sewer, so at 230 working days a year, you'll save 230*1.5*£2.27 = £783. Believe me, Southern Water make it difficult but nearly £800 a year has to be worth the hassle.
Vin