As for the safety of tap water. KNOW YOUR SYSTEM and know your country's laws. In a major industrialized country like the US or the UK, where the means exist to enforce the standards on the local public water system, and it is done routinely, it should be no problem If it is safe to drink, it is safe to take the other way as well. In some countries, standards may not be in place, and/or the means to enforce them may be limited.
If you are on a well, and you have any doubts about your well, you can always go out one night and pour a gallon of laundry bleach down it, wait 6-8 hours, and then let ONE faucet run for 2 minutes before you drink it, but again if it's safe to drink it's safe in an enema.
There IS one sorta-catch. Some water, especially well water is very "hard," That is it has a high calcium content. Calcium is very common in much of North America's bedrock. If you try to mix in soap, and the soap curdles instead of lathers, and leaves a lot of film behind, you have hard water. You might want to mix in some distilled water to get the soap to mix properly.
A lot of people don't realize this, but one of the reasons why NASA has embraced the "follow the water" strategy is that water is such a good solvent.
Distilled water is so pure that it's actually better NOT to drink it. Here's why: All other water, including bottled water and tap water contains SOME amount of organic minerals, usually less than is in your body.s own tissue, but SOME! Distilled water is so absolutely pure, it can actually get into the body and dissolve things like potassium, sodium, and calcium that your body needs. IT CAN ACTUALLY ABSORB NEEDED MINERALS RIGHT OUT OF THE BODY!! You won't hurt yourself drinking a glass of distilled water once or twice a day, as long as you are getting enough other fluid, but given that enemas are often two quarts or more, distilled water is actually MORE RISKY than tap water in mostg industrialized countries.