Steve, for sure the water tanks here seem cheap like all steel or galvanized products.
We had a water leak from the tank, seems like there's always a leak and it's a steel tank so I called our plumber and he noticed right away the bearings in our water pump were shot because of the noise and I knew something was wrong but? it ran like that for a couple weeks and the pump was close to being destroyed so good thing the plumber caught it.
The 1 hp electric water pump cost us 7000 pesos, it was a replacement pump back in 2012 but now I see they sold at the same Hardware store for 9000 pesos. I still have the old pump and it's quality but needs to be rebuilt so I need to get that done the rebuild labor costs are only 1000 pesos.
I've had to repair our steel water tank several times and it's covered in marine epoxy at the seams or on the very bottom area's.
The shut off switch's can be purchased at larger size Hardware stores or spots that sell the tank, they give you the option of fake vs original shut off switch's and the fake ones look identical to the real ones but at half the price, those fake switches are garbage, our current shut off switch cost us 500 pesos and has been on since the last pump rebuild but If I buy those fake switches I'll have trouble every 6 months.
Earlier this year one of the large 2" water pipes burst from rust and that ended up being a costly labor job that required 3 workers and also some cement work to keep the pipe from moving or damage from kids jumping on it, plus a ramp over the pipe, so with two large pipes and two elbow fittings and labor it ran us 7,000 pesos.