Probably not a "bad" idea but those lights are expensive. At least you would have an idea of the potability of the water though.

Some bacteria (such as E coli) can be eliminated by "shocking" the well with bleach. It's not too difficult to do.

If it is a shallow well OR is dug OR has some cracks in it (where bugs or mice, etc) can get in and die... you'll have a little issue until you correct it. Also, if the water table is high (especially if it's a dug well) you'll have an issue.

Around here I can go to the health dept and get a sample kit. I take a sample and give it to them and they test it, It's about $20 and if they give the all clear, that helps with liability.

If the place has not been lived in for a while shock the well. Easy to do. Even easier when nobody lives there.

Then get a bottle from the health department and get a sample. Don't take the sample from an outside spigot and don't put your thumb inside the bottle.

As long as you have shocked and cleared the bleach out you will get a good reading on what you have.

My place sat empty for a decade. I didn't shock the system when I got the water sample. I was going to the health department for another place so I figured why not. It came back good.

where we are, there are water labs that you can go to. They'll give you instructions as well as the container to put the water in. One of our labs closed down a few years ago but we found out that our local water board also does them (closer depending on the property for me to go there and was a bit easier). They usually will email you the results in a few days.

Basically, pour bleach in the well and then run the water in ALL LINES until you smell bleach and let it sit. Wait 24 hours (at least) and then go back and run the water in all lines until you do NOT smell the bleach (chlorine). They cannot test it if there is bleach in the water. So if there is (either you didn't run it long enough OR you poured too much bleach in it) just keep running the water for a bit.

Flow test - it should take about 5 minutes to fill a 5 gal bucket.

With a thin rope with a weight on it, drop it down in about 10 feet increments until it splashes. Take that measurement to see the static water level. Then drop it down into the well until you hit bottom. Again measure that length of rope with out dropping it all down the well. That is the well depth. Measure the size of the well casing. A 8 inch casing isn't half the water of a 4 inch - nope instead it actually eight times more water. You need to multiple 3.14 times to get the water volume.

Next run the well for about 40 or so minutes. Measure how much the static level dropped with constant use. Then wait about 30 minutes and measure it again to see how quickly the well recharges.

Now as for bacteria - it is common if the septic system isn't at least 50 feet from the well head. But that can be tricky - do you know where the leech field is at? Not typically, it is a general guess. If you do have e-coli you need to shock the well by using a half gallon of outdoor bleach. You mix up the water in the well by cycling the well pump.

Another thing to add about shocking the well.

When it has sat for the time frame and you start running water thru it do NOT get too close to the stream and touch your nose to the water.

I had a tenant that said the water had a sulfur smell. The county will do water tests. Came back positive e-coli. Had to have a licensed plumber or well person shock the well. then it had to be retested 2 weeks later. In the mean time they could not use the water for drinking. After the 2nd test came back the smell was still there. Ended up having a spin down iron separator placed and that got rid of the sulfur smell. I also put in a UV light which I change the bulb yearly.

Bottom line is if it isn't broke I wouldn't go messing with it. I was a major hassle, time consuming, and expensive to remedy.

On top of that, the tenant moved 3 months later. No one previously had complained about the water.

Oh and in my county, 30% of the wells fail an e-coli test. THIRTY PERCENT!!!!!

The UV lights required to kill E coli are EXPENSIVE to purchase, expensive to run (electricity) and expensive to maintain. Most of the ones that are less than $1000 don't do the required exposure and if you use it with a known contaminated source-- you are opening yourself up to be sued