Water and Sewer bill going up every month

[Frank Agyeman-Duah]

My tenant lives with her two grown up daughters who may be in their 40's. Tenant notified me about 4 months ago that her grand daughter and her son will be joining them for two months. The grand daughter and her son have been living there for about 5 months now. I realized that the water and sewer bill which is in my name gives going up every month. I increased the bill by $50 per month but it's still appears not to be enough. I'm contemplating on asking the tenant to let her grand daughter and son move out. This is a 3 bed apartment and now it appears tenant has about 4 relatives living with her. I need your suggestions. Thanks