Just looking for tips on how to best set it up and if there are better brands/materials to use to prevent or limit corrosion?

Subsequently, tenants reported multiple plumbing issues, including some corrosion seen on the external of the water heater.

For insurance, the tenants property is covered as personal property on premises, you property is under your coverage as property away from your premises or under your landlord policy as on premises, coverage amounts are different for these classifications.My lease also addressed personal property and substances kept on premises, restricting flammable, toxic, acidic or corrosive materials not normally found for or in residential properties and that common materials are stored in proper containers.

I literally test water for a living and have never seen water actually be discolored from corrosive water/copper.

If you have a fire extinguisher, a periodic inspection should check for of at least the following items:o Located in designated place.o No obstruction to access or visibility.o Operating instructions on nameplate legible and facing outward.o Safety seals and tamper indicators not broken or missing.o Fullness determined by weighing or "hefting".o Examine for obvious physical damage, corrosion, leakage, or clogged nozzle.o Pressure gage reading or indicator in the operable range or position. 7.

Common locations for supply lines to fail are where male threaded galvanized pipe is threaded into brass or copper valve and fitting bodies  (due to galvanic corrosion)  and hot water lines will rust up so badly as to start restricting water flow or begin leaking a decade or two before the cold side fails similarly.   

The way it was explained to me about water quality was if there was a possibility of corrosion then use the plastic fittings vs the metal which is what we do here in the Texas hill country.

Did it just fail from old age, corrosion, wood rot?

Hi @Ross Bowman,One factor to consider with a beach house is proximity to the water and factoring in the flood insurance as well as the additional maintenance cost due to the corrosive nature of the salt water. 

I recently purchased a pair of dewalt spring loaded needle nose pliers and sure it's a couple bucks more but the difference is night and day.Take care of your tools - the worst thing is rust or corrosion on tools.