Jdombrow,
Reverse osmosis systems provide water that is free of complex molecules providing drinking water that is of very high quality. Usually, because tap water is high in minerals and the minerals will plug up the RO membrane, traditional water softening equipment is needed prior to the RO process. Less complex molecules pass through the membrane with chlorine being the most common. Most systems hold water at this stage and pass the water through a bed of activated charcoal at the moment of dispensing thereby removing the chlorine. It's a judgment call as to whether this is pure enough for use in LP cleaning.
My home RO system dispenses water with total disolved solids in the 3 ppm range. Whenever my charcoal filtering system approaches the end of its useful life the disolved solids is in the 7ppm range. I can taste the chlorine at this stage. Interestingly, chlorine will gas off if left in an open container for a couple of hours.
The best water I've found is that used in the computer (chip) manufacturing industry. Not only do they purify through the RO process but also use a multi-stage ion exchange process; known as deionized. The problem is you need to know someone in the plant that can bring you a supply as the local manufacturers here have no way of selling water...they sell memory chips.
Probably the highest quality water is medical grade which is further purified by the distillation process to exacting standards. This is the type of water used by labratories. I don't know how an audiophile would go about buying such water since the suppliers are wholesalers to the medical research comunity.
There is no way to prove it but my reasoning is that highly regarded vinyl cleaning companies such as RRL most likely buy their water from a commercial vendor (Culligan, Echo Water, etc.) that supply bottled drinking water. These locally owned companies use the deionizing process, which when done properly provides water with total disovled solids in the range of 1 ppm when measured with inexpensive portable testing equipment.
The deionizing process is one where minerals are electrically charged through a chemical process. The charged water passes through a bed of resin that attracts these charged particles and removes them from the water stream. Some minerals respond well to negative charge and others to positive charge. That's why it's a two stage process. The process is very similar to water softening where minerals are exchanged for salts. The chemicals used in the deionizing process are caustic and dangerous for the lay person to handle and that's why you won't see a deionized system sold for domestic use.
Knowing what I do about how complex and expensive it would be to generate a supply of pure water just to clean LP's it is totally illogical to assume that RRL or any other highly regarded record cleaning supply company could afford to go to such extremes. The additives in the cleaning products would be chosen on their abilities to suspend any record bound impurities in the fluid during the cleaning process which is vacuumed off quickly.
Cleaning of vinyl has been discussed in these forums many times. While I respect what an audiophiles ears tell them about the effectiveness of certain products AND, RRL seems to have the best products as attested to by members I really respect, the mere mention of home brew using solvents that are readily available brings a hue and cry from the uneducated audience that such products as alcohol will somehow coax the vinyl into giving up substantial parts of its makeup. Hogwash. RRL and other suppliers keep whatever solvents they use secret and that fits in perfectly with the mentality of us as a user group. Voodoo often is the alter we worship at.
No offense intended here folks but I received a number of criticisms for my cleaning process in the past. If I didn't get my water from a local computer manufacuter I would buy it at the grocery store and look for water labeled as using the deionizing process.
