It doesn't have to be Distilled Water.
But, it should be clean water, best water without any heavy metal pollution, without PCB, Chlorine, Fluoride, ...
As most tap water in USA and many other countries contains added chlorine and fluoride, for the best results you should not use that kind of water.
Good water filters (reverse osmosis + active charcoal) can be used to filter tap water, and such water can be used for enema.
If you have an access to a clean, natural spring water, use it.
Whatever water you would not drink, do not use it in enema.
Distilled Water can also be replaced with clean rain water.