Basement water tank leak protection

I would like a method to contain water leakage from the hot water tank and well expansion tank/relief valve in my basement. The hot-water-heater drip pans would be great, except they are not made as a retrofit item. I have seen various rubber dams that can be sealed to the floor. My only issue with these are:
(1) For the water heater I would like to have a drain that I could attach to a hose or pipe to drain to my sump pum (about 30 feet away).
(2) They are not big enough to enclose the area around my well tank and water conditioners.
(3) They are only a few inches tall and would probably only hold about 10-20 gallons (I would like to contain my entire 30 gallon water heater if possible - I will also purchase a water activated valve to shut off supply and gas).
Can I build a small (4-5 inch) containment wall/dam? What is the best method and material (concrete, cinder block wall, waterproofing membrane)?
Thank you!