TDS Water Quality Tester

[silverp40]

Hi all

Does anyone have any experience with a total disolved solids tester?

Primarily used for testing water quality, I think it would be a good tester for on board filters as well as when getting water in places where water quality is suspect (like Mexico!).

Might also be useful for testing a watermaker output ...

Here is a small, portable one:

Thanks for any ideas!

[daddle]

TDS has little to do with water-borne pathogens. Need a lab for that. The meter is for monitoring RO performance in removing *dissolved* minerals, principally salts, not solid living things or toxins.

Chlorination is helpful for the pathogens. Water in Mexico is generally pretty good in the cruising areas.

[senormechanico]

There are lots of them on ebay.
Here's the one I use for my Spectra.
Works great, and cheap.

Digital LCD TDS Meter Tester Water Quality Filter Purity Pen Stick 0-9999 PPM | eBay

[silverp40]

Well, the TDs can also tell me if the water I obtain for the tanks has traces of heavy metals from old iron pipes, sediments, etc. Larger pathogens like girardia also read.

Also is good to know when to change the water filter for the drinking water...

Mr mechanico, do you calibrate yours? Do you have to buy a calibration kit/samples? Thanks for turning me on to this one - it is half the cost of the one in my pic....

PS Water in western Mexico, El Salvador, Guatemala is always suspect - maybe some fancier marinas have good filtration systems on their hoses....This has been going on there since the seventies at least in my experience (and sickness too).

[S/V Illusion]

These things should be outlawed as they can be dangerous for giving nothing more than a false sense of security. This is the kind of marketing the door-to-door snake oil salesmen use trying to convince unsuspecting people to buy their water filter.

If you want to know your water quality, have it tested properly by a certified lab which would never use this thing as it would cause them to lose their certification.

TDS is not an indication of anything significant and I really wish people would stop and think about these magic dust toys with some common sense.

[sailorboy1]

I use one probably 50+ times a week for industrial water testing. But unless you are testing your RO water it isn't going to tell you anything on the boat (well maybe except for whether your leak is potable water or seawater). TDS varies a lot from place to place and doesn't mean anything as far as quality of the water for drinking.

[silverp40]

All right, can it tell me if my water filter works or needs changing?

[belizesailor]

As others have posted, a TDS meter is useful for determining how effective your RO systems is operating, but tells you almost nothing about general water quality.

[Captain Bill]

Originally Posted by silverp40

All right, can it tell me if my water filter works or needs changing?

NO! I hope that is clear enough.

[silverp40]

Partial Quote from EPA Website:

"The EPA Secondary Regulations advise a maximum contamination level (MCL) of 500mg/liter (500 parts per million (ppm)) for TDS. Numerous water supplies exceed this level. When TDS levels exceed 1000mg/L it is generally considered unfit for human consumption. A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (lead arsenic, cadmium, nitrate and others) may also be dissolved in the water."

Ok, so we are in west Guatemala filling up tanks from the local town water supply that's been there for about 300 years via jerry cans. What means do I have to do a quick test of any kind and see if it is worth shlepping it back to the tanks? Looks all right, smells ok, locals say it's fine but they've been drinking it for years...and no labs anywhere for testing.

So if a theoretical TDS meter said about 300ppm and I take the water, would I make a mistake? I do need the water -we are quite low.

[S/V Illusion]

Originally Posted by silverp40

Partial Quote from EPA Website:

"The EPA Secondary Regulations advise a maximum contamination level (MCL) of 500mg/liter (500 parts per million (ppm)) for TDS. Numerous water supplies exceed this level. When TDS levels exceed 1000mg/L it is generally considered unfit for human consumption. A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (lead arsenic, cadmium, nitrate and others) may also be dissolved in the water."

Ok, so we are in west Guatemala filling up tanks from the local town water supply that's been there for about 300 years via jerry cans. What means do I have to do a quick test of any kind and see if it is worth shlepping it back to the tanks? Looks all right, smells ok, locals say it's fine but they've been drinking it for years...and no labs anywhere for testing.

So if a theoretical TDS meter said about 300ppm and I take the water, would I make a mistake? I do need the water -we are quite low.

Again, TDS is not an indicator of "safe". Just re-read the EPA reference
carefully. If you doubt the quality of the water and have no means of having it tested, it really comes down to what Clint Eastwood said - "do you feel lucky punk?" My experience is that there is always a MD or local health facility in even the most remote places and they would be your best source of advice.

I'd also mention that running the water through a carbon filter doesn't disinfect anything but only removes that which may taste bad thereby again providing a false sense of security.

[daddle]

Filter it to remove *solids*. Then a carbon filter if it smells bad. Then* chlorinate it in the jerry cans. Let it stand for a day. Then test for saltiness. You can taste saltiness when the TDS nears unsafe levels near 1000ppm.

In suspect areas there should be a 'taste' of chlorination in your tank water. That can be removed by simply letting the drinking water stand for a hour or with another carbon filter. Or just drink it if you are not a sissy.

That is my somewhat informed decision. The false belief that filters, either particulate or carbon, purify water of pathogens is common among cruisers. Cloudiness and bad taste never hurt anyone much. The unfilterable pathogens can kill.

* Chlorination of cloudy water is nearly worthlessas pathogens can hide in the solids.

[silverp40]

Thank you all for your generous help: daddle, Illusion, Don and belizesailor!

[bstreep]

Just one more, from a biologist. TDS is a good measure of dissolved solids in water. It is a terrible/inappropriate instrument for the quality of your drinking water. For measuring the output of a reverse osmosis system, it's invaluable, and cheap. For determining whether or not to drink water in Mexico? Worthless.

[GordMay]

Originally Posted by daddle

TDS has little to do with water-borne pathogens. Need a lab for that. The meter is for monitoring RO performance in removing *dissolved* minerals, principally salts, not solid living things or toxins ...

True, but if the R/O membrane is rejecting salt, it's likely rejecting most bacteria & virus pathogens, which are (almost) all larger than a dissolved salt molecule. Hence a TDS meter is useful for testing R/O output quality.