Actually, that's a bit of a lie. You can recycle your water, but we really don't suggest it. You're more apt to start regurgitating contaminants back onto your diamond disk, which will increase your chances of unwanted scratching. You also run the risk of embedding debris into the nickel of your diamond disk which will more consistently cause problems and scratching.
In the end, it's just not worth the potential hassle and aggravation that it will cause. If you don't have any plumbing in your shop and you really, really want to recycle your water to cut down on time, then you can download our PDF of creating a cascade water system that will cut down on contamination. The PDF file is listed below.
If you are only polishing, then it is perfectly fine to recycle your water and cerium, it will reduce your cerium costs and work quite nicely.