Building Construction, Renovation, Maintenance & Advice

Ecoli, Coliform and Mineral Contamined Water

"A Contaminated Well"

J. from Ubud writes:

Last month my two young children fell ill and were hospitalized with serious amoebiasis (and then dehydration). After regaining their health, a week later they both fell ill again, this time the diagnosis was bacterial e.coli infection. Among other precautions, we had our well water tested at Quantam Lab in Denpasar. The results have just arrived and show all things to be normal except 3 problems:
1) Nitrates high at 18.4 mg/L (max allowable is 10)
2) Coliform at > 2,400 mpn/100 ml 
3) Fecal coli at > 2,400 mpn/100 ml

As we live in a densely populated village neighborhood, I guess it is not too surprising that the well has been contaminated, especially during the dry season. Now, my question is: what can we do about it? We are renting this house, and before we sign a renewal contract with the owner, we need to know what we want to stipulate he must do about the well. 

1) Is this water safe for mandi and dishwashing?
2) How could we make it safe for drinking and cooking?
3) Is it correct that e.coli in this concentration can be killed just by boiling? Or is there a better remedy - adding chlorine, or another method? Any side effects to these methods?
4) Is it true that nitrates cannot be gotten rid of by boiling, and boiling makes it worse? If so, how can one reduce nitrate level in the water?

Firstly, I am not in any way a medical expert, my concern is with the operating efficiency, effectiveness and condition of your water supply. Perhaps Kim Patra may be able to clarify the medical aspects of the questions.

As a young mother J. is quite understandably very concerned for the health of her young children.

Let us first look at the test results that indicate above normal levels of nitrate, coli and fecal coli.

Nitrates in Water

Nitrate (NO3) is a naturally occurring form of nitrogen that is easily absorbed in water. The generally regarded maximum allowable level is 10 mg/L although for adults it does not become a major concern until you get to levels over 100mg/L..

Very young children (less than six months), however, are susceptible to nitrate poisoning. Bacteria that live in their digestive tracts convert nitrate to nitrite (NO2). Nitrite then reacts with hemoglobin, which carries oxygen in blood, to form methemoglobin. Methemoglobin cannot carry oxygen, thus the affected baby suffers oxygen deficiency. The resulting condition is referred to as methemoglobinemia, commonly called "blue baby syndrome."

Within several months after birth, the increasing level of hydrochloric acid in a baby's stomach kills most of the bacteria which convert nitrate to nitrite. By the age of six months, the digestive system is fully developed, and the risk of nitrate-induced methemoglobinemia is greatly reduced.

Most reported cases of blue baby syndrome due to contaminated water have occurred when infant formula was prepared using water with greater than 40 mg/L of Nitrate.

Nitrate can come from fertiliser runoff, from septic systems or from rotten vegetation.

It should be noted that we naturally take in nitrate in our food mostly from vegetables.

Coliform and Fecal Coli

>2,400 mpn/ml means a count greater than 2,400 per ml. Mpn stands for “MilliPore Nutrient Test”. The recommended standard in western countries is zero. Take note of the “>” which means “anything greater than” This is the maximum reading and would be the same for raw sewage.

Coli and fecal coli are bacteria that normally live in the digestive tracts of animals and humans. Rather than being dangerous in themselves they are used in these tests as “markers”. Their presence indicates that the water is contaminated and that other far more worrying pathogens such as giardia and cryptosporidia may be present. To carry out a full set of tests to search for every possible bug would be complex and expensive.

In J’s case her children have caught serious infections. The cause of the infection was her well which has been contaminated by raw sewage (either human or animal). This is particularly concerning in a country where the local population have a higher incidence of bowel dwelling bugs compared to western countries probably a result of poor quality of water supplies and high medical costs. Many local people simply put up with and eventually get used to bowel ailments.

One look at J’s well revealed a fundamental problem.

The well has earth sides and is not lined. This means that ground water can enter the well at any level in its depth. Groundwater just below the surface from a nearby septic tank or water passing through a layer of permeable shale can enter the well.

Wells and bores should be located well away from septic systems.

Wells and bores should also have lined and sealed walls so that water can only enter from the bottom. This ensures that the water in the well has been filtered through the ground before it enters. The deeper the well or bore, the more depth of ground the water passes through and the cleaner the water.

It is important that when a well is built the space between the hole that has been dug and the wall of the well is filled in otherwise water can simply run down behind the wall and enter the well at the bottom without being filtered.

1) Is the water safe for mandi and dishwashing?

No. The water is effectively diluted sewage. It has someone else’s fecal matter in it. Trying to persuade a young child to avoid getting water in his or her mouth is not being realistic.

2) How can we make it safe for drinking or cooking?

There are several methods including boiling, using chemical treatments such as chlorine, silver or iodine (4 drops per litre left for 10 minutes), ultra violet light systems and reverse osmosis. Note that carbon and sand filters will not kill or remove pathogens.

I, and I suspect most expatriates in Bali, use bottled water for drinking, cleaning teeth and cooking.

3) Is it correct that e.coli in this concentration can be killed just by boiling?

Yes, boiling is the most reliable method of sterilising water and boiling water at a lively boil for one minute will kill harmful organisms.

The most effective, but most expensive, water purification system is a combined system using active carbon filters, reverse osmosis and UV treatment. These systems have the advantage of not adding chemicals to the water so there are no side effects.

4) Is it true that nitrates cannot be gotten rid of by boiling, and boiling makes it worse? If so, how can one reduce nitrate level in the water?

Nitrates can be removed through reverse osmosis. Note that reverse osmosis is also known as Hyperfiltration.

In J’s case the nitrate level is not such a serious worry but reflects her fundamental problem - she has a poor water supply. She is best advised to find a better supply by installing a lined bore to a considerably deeper depth than the present 8 metre well. In her location probably 40 metres would be appropriate.

Copyright © Phil Wilson 2009
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

8 February 2017 Copyright © Mr Fixit,
Jl Bypass Ngurah Rai, Gg Penyu No 1, Sanur, Bali 80228, Indonesia
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