How to check the effectiveness of a water filter

If I wanted to check the effectiveness of a water purification method, how would I go about doing that? This is for contaminated water in the event of a disaster or while camping. Would you call up a lab? What would they charge you for something like that?


You could buy a TDS meter, they’re about $20. I wish I had one. But if you want to know if the water is safe for consumption, you might need to ask a lab.

This link is the commercial version of the water bottle I use.

I have never questioned this bottle because it was tested in flood conditions and are the best there are.
One of the KEY things you will find will be the very low flow of these filter bottles. T move the water through the filters and charcoal element (for taste) is a slow process.
This is a good light weight bottle to carry on trips to 3rd world country’s and mine has traveled more than me. It is packed for emergency’s only as it has a limit and that can depend on the clarity of the water used.
As for testing, call a water softening service and ask if you can bring in a sample.

There is no one test that will identify everything in the water. Labs run multiple tests to check for specific contaminates.

Usually for surface water the main issue is bacterial contamination and that’s what most your camping style filters are designed for.

Here is a basic pricing breakdown from a local lab I use.

In Massachusetts potable water supplies must meet the parameters for the General test. Some towns require more.

There are many additional tests that are only required if there is reasonable cause to believe the water was in danger of contamination from. For example rarely would anyone test or require a test for uranium so that test is rarely performed even though uranium in water would be very bad for you. If you had so a nuclear power plant next door, the need to test for uranium is a bit higher.

In flood conditions VOC’s(volitile organic compounds ie gasoline) become an issue so you’d want a filter that can cover that as well. Most can as activated carbon will pull it out.

Keep in mind however portable filters have very limited capacity depending on the contaminate, carbon can pull out a ton of chlorine but only a very small amount of gasoline. For a few days of drinking water for yourself those filters are great. If you’re trying to use it to quench the thirst of a dozen people you need larger equipment.

TDS meters measure the Total Dissolved Solids in a sample of water. It’s useful to measure the purity of tap water from distillers or RO units (indeed, that’s what I use mine for at work) but they rely on the fact that inorganic solids such as salts and minerals change the conductivity of the water, and that’s what they base the reading you get on.
Organic solids may not actually change the conductivity (sugar doesn’t, for example), and so it doesn’t actually help in determining whether a given sample of water is safe to drink. Indeed, a high TDS reading doesn’t even mean it’s bad to drink - tap water in some parts of the UK can reach as high as 300ppm, and water at 0ppm isn’t actually safe to drink in quantity.

So no, a TDS meter is not going to help in the situation the OP asked about.

What’s the method? (I’m guessing you’re using a common method and want to be sure you’re doing it right/it works in a specific set of conditions?)

CMC fnord!

But can it test a filter for potable water, eg Brita filters?

I think rather than trying to test, it would be better to have enough confidence in the filtration method that you feel it necessary.

I don’t know what new techniques are available, but traditionally if you have a liquid that has multiple components, you would purify/separate using fractional distillation. With tap water though, that’s not your objective. You just want to isolate the water.

If you use a distiller, it should in theory, evaporate everything with a boiling point lower than water. Hopefully there won’t be much of that though. Some volatile organics (VOCs) maybe. Any dissolved solids will be left behind. If there are things with a higher BP too, some of that will come over too but I have not idea what might fall into that category.

As was already mentioned, an activated carbon filter on the output should take care of any VOC’s. The water still won’t be pristine, even after multiple distillations, but it will pretty good and certainly better than a Brita filter.

What are the kind of TDS meters that measure light transmission through the sample?

Aren’t Brita filters activated carbon filters? :confused:

I’m sure, but they’re too small to give consistent results over long periods. As substance adhere to the carbon, it gradually becomes ineffective.

The distiller I used to use had a brick of the stuff the size of 2 decks of playing cards.

Yes, and that is pretty much what they are for. But Brita filters are designed mostly to filter out calcium carbonate, which is the chief cause of limescale, and your tds meter will certainly measure the effectiveness of that. But this assumes that your water is actually safe to drink in the first place. It won’t remove legionella, for example, and the tds meter won’t detect it. I assume other waterborne bugs would be similarly unaffected, and in the OPs scenario, that’s really what you are looking for.

testing is an issue private well owners face.

in the USA a state’s natural resources agency will have a list of testing labs for water, some private and some government affiliated. you will find different tests; bacteria, common metals, less common metals, some pesticides, some herbicide. you might have a price maybe $25 to $50 for many tests. time between test and report is usually weeks.