some thoughts from Dozer
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Water Filtration and Pure Water Tester

image img_0203.jpgRecently I had a service company out to do the yearly service on my filtration system. One thing has become clear since I purchased the stainless filtration system, which consists of 3 containers each holding one granular element, carbon, magnesium and an ionizer. The brand we bought, Dema, (purchased at homepro) is probably not the way to go. First off, it is designed to be as difficult as possible to change the filtration agent. The bottom needs to be unscrewed and jiggled and flushed slightly. If it is moved too much the pvc will break and need to be reinstalled.

Secondly, according to the technician spare parts are not interchangeable with other brands.

In any event, the entire process took two guys about 2 hours to complete. Each container holds 20 liters of filtration agent.

image img_0209.jpgI was quite impressed with this hand water checker that the technician had. You put it in rain water and it registers impurity level of 10. Our well water was 170, which is OK for shower water, but he said the more ideal range is 150. I am most interested in finding out more about these water testers, how they work and should anyone know anything about them, please let me know. The technician said it was ‘A secret of the trade’ (where they come from). Oh gee, I see this same one on Ebay for $17.98, think I’m going to order one!

I really like the idea of having this new gizmo. I will be doing a lot of water testing, for example to measure the raw well water vs. the filtered water. Also, I am more tempted now (than before) to buy a drinking water filtration system, a good one costs about 10,000 baht. One of my hold offs before was, how do you really know if it is working? We’ll, with this baby I think I’ll know!


  1. Hi Dozer

    send me more details, I wilol check it out but it sounds like BS to me, probably something simple that just tests the electrical conductivity of water (pure rain water is nearly an insulator)

  2. There are a couple out there on the internet. For $18 it can’t be all that great can it? You can see them on ebay by searching for water purity tester. Let me know what you find out. I think that is how they work also, the electrical conductivity of water.

  3. I’ve got a few concerns about these filters. I’ll add them here, but if anyone wants any more info I’ll put a fact sheet together.

    As has been stated above, the meter used by the service guy is a “conductivity meter”, it measures the flow of electricity in the water – the more impurities, the more electricity flows.

    However not all impurities are bad news and some are essential to good health.

    My particular concern is the use of de-ionising resin (the small brown beads in the filter), these remove ALL impurities, including the good ones, and in particular Calcium and other minerals.

    The water then becomes ion hungry and will leach ions, and Calcium from your food/body when you drink it.

    I don’t believe de-ionizer resin is necessary It is certainly not necessary if your water supply is from rain water and I doubt very much it is necessary if you are using mains water (most of which is rain water).

    Mirco Filtering is all you need Assuming that you are not taking your water from an area which is contaminated with heavy metals, mercury, lead, cadmium etc (in which case you should be shipping your drinking water in from outside the area. There is no need to use ionizing, micro-filtering will remove the biggest threat to your health – Viruses and Bacteria.

    Filters are available down to 2mircrons but 4microns is sufficient to remove even the smallest of viruses and will still leave all those good salts and minerals in the water to keep your bones and teath healthy.

    I would certainly not use de-ionizing and I would advise anyone who has young growing children or a history of bone problems in their family not to either.

  4. Hi itchy

    quite right, though i never thought of de-ionised water as dangerous to health – of course ive only ever come across it in use as boiler feed water, not potable water

    one problem with rainwater up country is that it is too pure, ie no minerals, so kids can sugffer from calcium deficiency particularly in poor areas. I was considering recommending using sea shells suitably cleaned, boiled and then ground up coarsely and placed in the bottom of rainwater jars. although calcium carbonate is fairly insoluble it will migrate of time particularly if the rainwater is slightly acid. better than nothing. of course the locals get their calcium from fishbones and land crabs (som tam) and milk if they can afford it for the kids. this hi calcium milk is a real rip off at 40 baht a litre, standard full cream milk is sufficient.

    I have noticed in the big supermarkets that when tbey sell these water filters, they dont seem to stock the correct replacement filters

    with the kind of muddy tap water we get, these filters would fail in a few weeks. you would need a sand and charcoal prefilter first. easy to make using cement rings as used for septc tanks 70 baht each, 3 is enough, fill it with washed builders sharp sand, not the yellow sand.

  5. Teslar I have very muddy well water and used these small Mazuma sediment filters, they all failed. Then I installed 4 septic tank cement rings going up 3 meters, fiiled 30 % with coarse building gravel. I throw very little diluted Chlorine in this tank. All the dirt and excessive iron settles on the floor. See also my photos how to build a swimming pool, included some filter photos.

  6. I’ve never heard of any problem arising from drinking water that is too pure. All of the minerals present in drinking water are also present in your diet if you eat healthy food. I’ve never heard of pure water leaching minerals from your body. If you consider the amount of water you drink in a day and how dilute the minerals are in drinking water you will see that the amount of minerals you get from drinking water is very very small. Compare this to the amount of minerals you get in the food you ingest. I think you will see that the mineral intake is much much larger in your food than in your water. I would be interested in any credible information that supports drinking water as a significant source of minerals.

    I have a water filter made from well rings containing sand like others have described. My ground water smells noticeably when coming from the ground. It smells and tastes fine after running through the filter. I use no charcoal and no chlorine, just sand.

  7. This link has information about minerals in water and health.

    I would point out that de-ionized water is not just missing minerals, it is ‘ion hungry’, it leaches minerals from your body and therefore has a double impact on your bodies mineral intake.

  8. Hi itchy

    many thanks for the interesting link on lentech

    children up in the northeast have suffered from calcium deficiency. rainwater is commonly used for potable water. i dont think it is in the same class as demin water as has never been show to be hazardous if harvested from clean roofs and gutters and kept in clean cement jars. I have never found rainwater as having a soapy taste as reported under “softened water”. Indeed when i return periodically to london I find the tap water has a nauseous taste – but it makes a good cuppa

    you can make your own activated charcoal by heating natural lump wood (not bbq briquets) charcoal ground up coarsely up in a tightly closed container to around 400C (i beleive from memory). It must be allowed to cool completely before opening. I saw thgis on the net somewhere, have not done this yet

    I need to construc as sand filter/settling tank as posted here because otherwise, i am washing my clothes in muddy water.

    I am going to build a settling pond for the waste detergent water and try various plants (papyrus?) to see what will eat up the phosphates.

    all interesting stuff, never a dull moment up country


  9. I have always had concerns about domestic water supplies in Thailand especially those derived from local wells. If you are in well populated area then you must take into consideration that most dwellings including yours will be using a 2 compartment septic system that runs its leach into the local ground. If properly designed and maintained, these systems are very efficient in breaking down solid waste from toilets. However, they do not remove all harmful bacteria. The fact that there is no regulation or control over where and how the leach is discharged makes me wonder just how much of this harmful bacteria ends up in the water of local wells. You must also consider what goes down the drain in local business and factories.

    Last year I gave a sample of my well water to a friend for analysis. They found it to be unsuitable for drinking due to trace levels of bacteria. Mineral metal and other compound levels were found to be satisfactory.

    Here are some guidelines for water testing.

    Test for coliform bacteria, TDS , nitrate and PH. Best time to test is in after rainfall following dry period.

    Every 3 years test for sulphate, chloride, iron, manganese, lead.

    Filtration systems should be regularly checked and maintained.

  10. This filtration system isn’t adequate to produce potable water, we may add another filtration system in the house later for this. I think the notion of the meter is simply to a basic test to see if impurities are being filtered out and that the water you are taking a shower with is basically clean. At one place I was on city water and it was really dirty. At least well water is better than that!.

  11. I’ve read this thread with interest since I’ve been using a reverse osmosis unit for the past 6 years and have been very happy with it. It’s a lot more convenient than buying the big bottles and tastes pretty good. I haven’t really worried much about the downside of removing essentially all the minerals. The lenntech reference from Itchy was interesting and well written but they’re a little suspect since they have a product to sell. So I looked on the Google and found the WHO article at

    It confirmed most of what lenntech’s article said. So, now I’m looking for a re-mineraliztion like they sell: or

    Any ideas where to find them?

    For the TDS (total dissolved solids) meter, you’re right teslar robin and dozer, they aren’t much of a purity meter because they only test the conductivity of the water. But I find that useful to see if my RO membrane is still working. I got mine 2 or 3 years ago at SBO Technics (on the right side just past the Highway 36 turn off on Sukhumwit). I don’t remember exactly what I paid for it but it was less than 1,000 baht.

  12. This post confirms my use of carbon filter/ultra filter/ultra violet radiation / from a mazuma uf3uv of course ahead of this unit is a combo sand & charcoal filter & between these 2 units sits a 5micron particle filter this article states that demin units remove esential minerals be it either from ro or demin resin beads a good point to consider for aged persons and growing children

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