My 88-year-old father lives at home and the house needs serious repairs (plumbing and electrical). He doesn't want us to help. What are our options?

Have you thought about taking him out for a day trip and having professionals come do the repairs anyways? He will be mad at first but he will thank you in the long run for helping him live a better life. Explain you got it taken care of because you love him, regardless of what he says. Sometimes it's not a matter of them "allowing you" sometimes they say no and what they really mean is I'm too embarrassed to ask for help because I'm the adult and supposed to be caring for you, not the other way around. Reassure him that it is okay to have help and that he is not burdening anyone by needing repairs, that it is normal to need them and have them done, especially if one can afford them or has help to have it done.

Gtoth3, sometimes us old timers can manage things the way they are. Curious, how serious are the problems? Maybe the issues aren't serious to your Dad. Your Dad's parents lived through the Great Depression where one had to make due with what they had, and they passed on that idea of thinking to their children. I know my parents did.

Any time I noticed my aging parents needed something to fix, I figure they got this, maybe it is something that isn't important to them. Their old dishwasher stopped working, so they hand washed the dishes, and never did replaced the dishwasher.

In my house, I have a lot of make do items, duct tape was made for a reason :) Yeah, I get the things fixed, but in the mean time it's not hampering my way of living. Serious matters, like replacing the roofing/wider gutters, done that as that was important due to climate change with heavier rain falls.

If he is competent, it's his choice.
If he isn't competent you need to address things, and that would be more than just the repairs to the home.

If there are safety issues you might contact the Building Department in the Town/Village/City where he lives.
If there is no water or electricity you could contact the Health Department or even the Fire Department.
A call to your local Senior Service Center might help as sell, most have Social Workers that could follow up.
APS or a call to your States Elder Abuse Hot Line number. They also take calls on Self neglect or anything that might be a danger to either Health or Safety

You can APS and report these issues with your fathers house and they will come out and investigate. If it unsafe for your father to live there, APS will take the necessary steps to either help point him in the right direction to get things taken care of or remove him from his home.