The 'Anti -Tap Water' brigade are mostly wrong.
Think about it. The impurities in tap water, are in the ..errm .. tap water.
So.. if you do not leave tap water to evaporate on your records, you will leave little or no residue.
Generally, I find most s/h records ok if just played and brushed with a decent anti-static brush.
Filthy records can be cleaned thuslywise:
Place a clean old newspaper on a flat surface.
Place record on newspaper.
Apply a sensible amount of water, mixed with Isopropyl Alcohol. (Proportions are not critical.. one is simply carrier for the other, but obviously economy counts. I go for about 10-15% IPA)
If you can't figure out a 'sensible amount', you are better not bothering.
Use a plain carbon fibre record brush to distribute the liquid around the grooves in a circular motion, until you get the 'feel' that you have 'worked' the solution well into the grooves.
Turn record over and repeat for other side.
Take the record to a COLD tap and rinse off, avoiding wetting the label.
Place the record carefully in a dish rack or otherwise support vertically. Leave for no more than a minute or so.
Most of the remaining tap water will migrate down the grooves and drain off the record.
Last traces can be removed by taking a Kleenex tissue (Other tissues are available) and folding it around both sides then running it around the disc until dry.
There will be very little trace of solid residues from tap water, and a lot less dust, grease and general crud.
Job done.
That will be £1:50p per record on an Honesty Box basis.
Thank You.
Mull