Legal help on a shared well and septic

[Bill Straw]

I purchased a home I was originally renting, this was over 10 years ago. After the purchase the title company didn't find that the well and septic, both on my property, are shared by the other home that the guy I bought home from owns. He has since been paying for the use of well and septic. Is this even legal and do I have to continue doing this? He did just cover the cost for some repairs and pumping of the tanks. Which will be split 50/50 as per a verbal agreement with my wife.