What is the average experience of your trustworthy drain leak repair installation staff or do you subcontract out the construction? Do you hire only licensed and bonded sub-contractors?
Before beginning, make sure you have chemical goggles and protective clothing. You need to take note that acid wash is only for concrete pools and not for those with vinyl covers.
This around the clock availability leads to the second thing to look for in your rescue personnel. Are they available at all hours? Saying you are and actually local water heater repair service picking up the telephone are two different matters. Do they offer at least two numbers, one for regular business hours and one for after hours? That is what you are looking for. And if they advertise dispatch vans, all the better for speedy replies.
If you live in a small community then there may be a plumber who will do 'out of hours' emergency plumbing repairs without charging a massive call out fee. A plumber that is willing to help his neighbours out in times of need is worth his weight in gold.
Last but not least is don't hire someone just because they gave you the lowest bid. Next don't hire some handyman that does odd bathtub replace jobs, in some cases they can cause you more problems that down the road it will cost you more money to fix what these handyman broke or did wrong. Sometimes the lowest bid is going to cut corners and not do the job right or when they get there and start doing the work, they keep saying they are finding more and more wrong and you end up spending more than what you should have.
So now you have a solid house. By that I mean, plumbing, electrical, heating and air-conditioning, roof, foundation and overall good structural integrity.
Finally, at the beginning, take the time to get quotes from several plumbers and potentially on non-emergency, lower cost jobs. Get a feel for the plumbing company and see how well they fit with your needs. Meet the plumbers in person. Then, when an emergency plumbing problem arrives, you will have a much better solution when time is of the essence.