Hi - just posting this to help all u newbies - from my experience I would recommend a system on
www.gapswater.co.uk, it has a 4040 membrane and a carbon and sediment pre filter, it costs £600 including vat and should allow you to fill a tank with tapwater in the back of your van which u connect to the ro system so the water purifies as u use the polebrush, All u would need to add to the system is a pump (should not cost more than £60 - £100 tops, and the water tank ( i think u can buy this on the same site for approx £70 or else get one from ebay for around that price. If u want your tds reading down to 0 then get one of their resin filters aswell, they cost approx £100 (u can get cheaper depending on size) and then u just need a pole which apart from the site i've mentioned, u can also get from a few good sites include gardinerpolesystems and chiccleaning and even wintecs the whole set up should cost under £1000 half of what i paid from one of the big boy companies(Ipaid £2000 for my system) and this system comes with full maintanence instructions and troubleshooting guides which are INVALUABLE as I was not told how to maintain my system and it cost me a lot of money to repair costly mistakes. You will have to buy a 10 inch carbon filter and a 10 inch sediment filter (all available on sites I have mentioned) every time your tds reading gets around 10ppm and you will have to flush your membrane out daily for one minute by opening up your flow valve then readjusting it till waste water and pure water are running at approx same speed as each other, this will prolong your membrane life (which costs around £200 to replace but if u flush it out daily for 1 min should last over 5 years , you will know when it needs replacing cos the pressure of your water flow will start to drop. if you do end up getting a resin filter attatched to the system, you will need to replace the resin approx every 6 months or so (depending on how frequently u change the carbon and sediment filters, which if u are unsure, just open the two little filter containers (or housings) and see if their looking really brown, u sometimes get away with rinsing them out and making them last a bit longer , but it is only a few quid each to replace and its better to pay £8 for a carbon filter that removes chlorine than not replacing them and the chlorine getting into your ro membrane and knackering it-costing £200!. some people use the ro-man and merlin systems but from what I have heard u have to spend hours purifying water BEFORE you put it in tank on van as they cannot purify fast enough to purify water to feed your pole whilst working and also need filters etc changing more frequent costing more money in long run (correct me if i'm wrong guys) some people also just use a big resin tank and no water filter system , but this goes through a HELL of alot of resin and as resin costs approx £70 - £85 a bag it would cost approx £1000 a year in resin , compared to 1 bag used per year with filter system so I would not reccommend! total maintenance costs for water filter system (including 1 x25 litre bag resin that should last 1 year (or approx 3 fills of filter) and approx 3xcarbon and sediment replacement filters should come to no more than £100 -= £110 and the cost of a replacement membrane £200 spread over approx 5 years = £150 in total running costs per year, I hope this helps out newbies out there or anyone generally in the dark about ro systems -