What should I do if I find that I have proof of income but no running water? Can I use my parents' tap water? I bought the house alone.

Unless you buy a house in the name of your parents, you can directly interview the bank employees when applying for a mortgage. If you don't have a serial number, you can deposit the money in the bank you want to borrow, and then ask the bank people to apply for it for you. Generally, after you meet the requirements in all aspects, this serial number has little effect on your loan. In addition, if it is purchased in the name of parents, the parents' conditions must meet the requirements of mortgage.