Water Filters

Depends on the contamination. The PUR probably will remove chemicals but IDK about bacterial contamination.

First you need to ask your LL why the water isn't "good for drinking" and then see exactly what the proposed water filter actually removes from the water to see if they're compatible. I've lived in many places throughout the island and not one of them has had a fancy filtration system but in only one place did I not drink the water as (although it was tested and deemed potable) it just never tasted very good!

we have city water, we have a whole house filtration system and a britta

It will depend greatly on the quality of the water that is going through the filter in the first place, which is to say, it is unknown... I have a Brita faucet filter and have been using it for years now and have had no issues... I did a test before and after installing it... Before it had this horrible taste and a bit of smell... Afterwards it was A-Ok...

My health is Ok and it saves me quite a bit of money and also having to deal with carrying water bottles at the supermarket...

I think many landlords say the water isn't fit for drinking because they don't want to take responsibility for maintaining cistern to drinking quality.

Very few filters purify water. I agree with STT, ask landlord. You can have the water tested at Ocean Systems Lab, but you can't correct if any contaminants.

I boil cistern water for my tea and use it for cooking, because that too will be boiled, but drink bottled if not boiling.

I think you need the cistern water so you can build up your immune system. What doesn't kill you will strengthen you. I've been drinking it for years.

You can purchase and have installed an under the sink UV system and take with you when you move or ask landord if he'll buy and install. You pay for servicing and maintenance while renting. The UV systems kill bacteria and makes water quality taste issue go away.

He can also install a sediment filter on the water pipe going to pump.These require monthly change of filters depending on how dirty cistern is but do not kill bacteria.
You can add clorox to cistern water to cut down on bacteria if cistern cover is accessible.

Keeping a roof and gutters clean and covering openings for intake and overflow pipes with screen also cut down on creepy crawlies getting into cistern and dying in your water.

If worried about drinking the water, do you really wish to brush your teeth, bathe, cook and do dishes with the water? As ms411 mentioned you can have water tested.
You'llend up spending more on PUR and britta filters, buying and lugging drinking water so have a chat with your landlord. It will improve his property so what can it hurt to broach the subject?

The faucet mounted filters typically utilize charcoal, which does a good job improving taste and odor but does not remove bacterial contamination in the water. Most filters will have a warning on the package stating do not use with water of unknown quality (such as cistern water) for this reason. In fact, charcoal is an excellent breeding medium for bacteria and if there is bacteria in the cistern the filter will simply concentrate it. Of course, not all bacteria is harmful, and even if it is harmful the effects will depend on the type and quantity consumed.

Adding regular unscented bleach (5.25%) to the cistern will kill all bacteria present, assuming you add enough to achieve a 2 ppm chlorine concentration. To determine how much to add, you first have to know how much water is currently in the cistern. Measure and multiply the length of the cistern by the width of the cistern(s) to determine the square footage. Multiply that number by 7.48 to determine the number of gallons per foot of level in the cistern. Divide that number by 12 to determine gallons per inch and then multiply that number by the number of inches of water currently in your cistern. Once you know how many gallons are in your cistern then add 6 ounces of bleach per 1000 gallons in the cistern, which should sterilize the cistern. However, this is one time batch sterilization and after a week or two there will not be any chlorine left in the cistern, which is why you should repeat it every month or so.

If you add enough bleach to sterilize the water then you may be able to smell and taste it. That is where having a charcoal filter will help as it will remove most of the chlorine. If you look in your cistern and there are frogs or mosquitoes present then you need to add bleach. The frogs will move out and the mosquito larva flushed into the cistern via the gutters will die. Having screens in your gutter downspouts will keep leaves from being flushed into your cistern but you have to keep them clean or they will eventually keep water out too. And I have found dead decaying rats in gutters, so even a screen in the downspout will not keep all the bodily fluids, etc. from being flushed into your cistern when it rains.

Personally, I do not drink anyone's cistern water except my own because I have a ultraviolet water filtration and purification system that I maintain in good working order and I chlorinate my cistern. While others may have a purification system at their house I have seen all too many owners who knew nothing about them but still had a false sense of security about their water quality even though it turned out that their system was bypassed, the UV lamp was burned out, or there were no filters in the housings. Or even though they added bleach to their cistern they did it in insufficient quantities, such as a cup of bleach now and then when it rained, to be effective.

The water testing labs here only test for the turbidity (cloudiness) and PH of the water as well as the presence of coliform bacteria (a harmless indicator bacteria) and e coli bacteria (not so harmless). They do not test for chemical contamination of any sort. And even if you do have your water tested and it turns out good, that does not mean a rat did not die in your gutter the day after the test...