Hi Glen,
I've posted this calculation several times in the past, but here goes again.
An 8" dia x 35" high demin column holds about 21 litres of resin. Resin's available at £60, plus £10 carriage plus VAT, so the actual cost of the resin in this particular column is 21/25 x (£60 + £10 carriage) + VAT = £69.
This column will remove 500,000 units of TDS, so if your tap water is 500 ppm TDS, it will purify 1000 litres, at a cost of 7p/litre. If you're lucky, and your tap water's only 50 TDS, the cost drops to 0.7p/L.
Obviously, using resin on its own is a cheap and cheerful way to get started, but the running costs can be prohibitive. If you don't have 50 - 100 TDS tap water, you really should consider getting an RO, and ought to go for the most productive one you can afford.
Not all high output ROs are expensive. Have a look at a selection by clicking on the link
http://www.andwat.co.uk/acatalog/Reverse_osmosis_units.htmlYours,
Andrew
