When I cleaned records using a Loricraft point-nozzle vacuum, the most critical step was the rinse. For that I used Nerl Reagent Grade Water from Fisher Scientific - it came in 5 gallon (44lb) boxes and was expensive, largely thanks to shipping costs. Reagent Grade water is primarily used in biological laboraties and others where ultra pure water is required for test integrity, etc. It works great for cleaning records but I've come to the view that it overkill and too costly. If you have a university near you, go to their Biology Department who probably makes their own; they may be able to supply you with some.

For ultrasonic cleaning, distilled water is fine. Get a TDS (total disolved solids) meter, $10-$20, and test your water. Distilled water should test at 0000ppm (parts per million), indicating no dissolved solids. Adding IPA and/or a wetting agent should still yield close to 0000-0001ppm.

That's great for a fresh round of record cleaning. BUT, the water will get dirty from cleaning records. If you air dry (fan or natural evaporation) it is the dirt in the water on the record that will remain on the record. Use that TDS meter at the end of a cleaning cycle to see where the water is now. There are 2 ways to deal with this: i) multiple rinse steps with clean distilled water or ii) actively filter the water in your ultrasonic cleaner.

It's all covered in this article:

tima’s DIY RCM – follow-up #2: Compelling Changes – Improved Results

While it is important to start with clean water, it is the water on the record when it dries that matters most.

Here is an article on Differences Between RO and DI Water for Parts Cleaning, Washing, and Rinsing
[DI water is deionized water]

I use Aquafina water in my AudioDesk Pro

Distilled water is great . . . and you can use it in your iron when you do clothes, in your C-PAP if you have trouble with snoring, use it in your humidor if you are a cigar or pipe smoker, and you should always use it in your car or motor-cycle batteries.

And, you can actually drink the stuff if you are so inclined.

So. by all means, keep a large supply on hand "just in case".

And, oh yeah, you can use it in your record cleaning machine too!!!!!

and you can use it in you live steam engines as I do !

So far it's working beautifully. I played 3 records yesterday and no buildup on the stylus. One record was an older vinyl that I had picked up at a used record store. Sounded like brand new after a cleaning.

It looks like the train is outside. Can you give some details?

For a good explanation about reverse osmosis, don't forget to also have a reverse osmosis-based water filter that can remove viruses and bacteria in water.

Distilled for sure, listen to your wife!::D

24 500ml bottles of Aquafina for less than $5 at Target, King Soopers, etc. works for me. Works for Fremer, too!

That's about 12000ml or ~3.2 gallons of Aquafina. One should be able to find 5 gallons of distilled water for $5, not quite 19000ml. Aquafina claims a TDS average of 4; distilled water TDS is 0. That's to start cleaning. The important gauge is how clean is the water on the record when it dries.