I guess at this stage, the discussion has gone beyond off topic. IMHO, the answers seems to be pretty conservative and cautious; many alternatives were suggested. May be its due to the nature and the risk associated with lightning and naturally being cautious of it.

So,it was implied that if the power supply wires are going towards the sky, (rather beyond a critical elevation, that might depend on the location and features), then a Faraday cage, and a lightning arrester are needed. As advised by MrChips,

You need:

1. A lightning rod.
2. Power cable inside rigid metal conduit.
3. Faraday cage around your device.

But if the device is at a lower height, just as tall as a roof top of a house,(say that has a very low probability of getting hit by a lightening), yet, it seems to be at a probable risk because I am putting up a conductor. Now I think of how lucky was Benjamin Franklin to fly that kite.

Hmmmmm....given that some scientists shoot rockets into thunder clouds to cause lightning discharges that then follow the wire down to the ground, the answer is "probably".

So I guess, however small, simple and low budget the project may be, we have to respect Mother nature.

You could try a solar panel and battery powered sensor and a radio link.

IMO the best solution will be to place the battery with the device itself and then use a solar cell to keep the battery charged... OK now I have to climb up to the water tank back. Oh by the way, how about a method of intermittent charging of the battery from ground level. When there are not storms I can charge the batteries and then roll up the wires. Will there be sparks from the wire ends? Do I have to maintain a minimum gap from the wire ends?

 

the tank is for drinking water.

OK. Then why are you mounting it 28 feet high? 12 PSI is not very much pressure. Sure, gravity will suffice, but if you're going to run a pump anyway then why does it need to be so high?

Not trying to pick apart your project. Just interested in helping you make a most efficient project possible, spending as little money as necessary while achieving the same results or better.

I've seen trees struck by lightning, so anything elevated can become a point for lightning to strike. Especially something well grounded. Having your tank at ground level will negate the fear of lightning strikes. Besides, being plastic (of sorts) a lightning strike would likely burn a small hole in your tank causing potentially a leak.

My drinking system consists of a Reverse Osmosis system that has been modified to be more efficient, produce more pressure and has twice the normal capacity. Not enough for long term drinking, but that's something that is a project for consideration. So far I've imagined a water tank in the basement with a pump capable of pumping water as needed for drinking. I've also considered a rain water collection system for water for other uses other than human consumption. Should I decide to filter and purify that water - that, too, is another project. Probably won't be done for a few years yet. If ever. But it never hurts to be prepared. Beside, if we face a water shortage it'd be nice to be able to depend on an extra source of water.

Interested in knowing how you proceed and how things turn out for you.

Tony. ")