World Health Organization paper on the risks of demineralized water
with expert references:
http://www.who.int/water_sanitation_health/dwq/nutdemineralized.pdf

I don't have time to look at the current version this week but here is
some info from
http://ferrethealth.org/archive/FHL8423

>BEGIN QUOTE
>Demineralised water is highly aggressive and if untreated, its
>distribution through pipes and storage tanks would not be possible.
>The aggressive water attacks the water distribution piping and leaches
>metals and other materials from the pipes and associated plumbing
>materials.
> ...
>Preliminary evidence was available that some substances present in
>water could have beneficial effects on human health as well as adverse
>effects...
> END QUOTE

and later in the paper:

>BEGIN QUOTE
>The possible health consequences of low mineral content water
>consumption are discussed in the following categories:
>
>Direct effects on the intestinal mucous membrane, metabolism and
>mineral homeostasis or other body functions.
>
>Practically zero calcium and magnesium intake.
>
>Low intake of other essential elements and microelements.
>
>Loss of calcium, magnesium and other essential elements in prepared
>food.
>
>Possible increased dietary intake of toxic metals leached from water
>pipe.
>
>Possible bacterial re-growth.
>END QUOTE

So, now to the sections that relate to the second list:

BEGIN QUOTED SECTIONS which are trimmed and which contain my own words
in brackets to avoid copyright violations. Please refer to original.

>Distilled and low mineral content water (TDS < 50 mg/l) [is]
>reported to be less thirst quenching (WHO 1980)
> ...
>Histology did not reveal any signs of erosion, ulceration or
>inflammation... Altered secretory function in animals (i.e., increased
>secretion and acidity of gastric juice) and altered stomach muscle
>tone were reported in studies for WHO (1980)
> ...
>It has been adequately demonstrated that consuming water of low
>mineral content has a negative effect on homeostasis mechanisms,
>compromising the mineral and water metabolism in the body. An increase
>in urine output (i.e., increased diuresis) is associated with an
>increase in excretion of major intra- and extracellular ions from the
>body fluids, their negative balance, and changes in body water levels
>and functional activity of some body water management-dependent
>hormones.
>[Remember that much of cellular communication and other functions
>require the right amount and balance of ions, no matter what the
>charge (negative or positive). Robbing the body of needed ions can
>be dangerous.]
> ...
>1) increased water intake, diuresis, extracellular fluid volume, and
>serum concentrations of sodium (Na) and chloride (Cl) ions and their
>increased elimination from the body, resulting in an overall negative
>balance if it is not adequately compensated from food, and 2) lower
>volumes of red cells and some other hematocrit changes (WHO 1980).
>...[Decreased] secretion of tri- iodothyronine and aldosterone,
>increased secretion of cortisol, morphological changes in the kidneys
>including a more pronounced atrophy of glomeruli, and swollen vascular
>endothelium limiting the blood flow. Reduced skeletal ossification was
>also found [in when water low in minerals or lacking minerals was
>consumed]
> ...
>Results of experiments in human volunteers evaluated by researchers
>for the WHO report (1980) are in agreement with those reported in
>animal experiments. Low-mineral water markedly: 1) increased diuresis
>(almost by 20%, on average), body water volume, and serum sodium
>concentrations, 2) decreased serum potassium concentration, and 3)
>increased the elimination of sodium, potassium, chloride, calcium and
>magnesium ions from the body.
> ...
>[The following section clearly described some of the ways that
>distilled water consumption can be hazardous.]
>The German Society for Nutrition reached similar conclusions, warning
>the public against drinking distilled water (DgfE 1993). This warning
>was published in response to the German edition of The Shocking Truth
>About Water (Bragg and Bragg 1993), whose authors recommended drinking
>distilled water instead of "ordinary" drinking water. The Society in
>its position paper explains that water in the human body always
>contains electrolytes (e.g. potassium and sodium) at certain
>concentrations controlled by the body. Water resorption by the
>intestinal epithelium is also enabled by sodium transport. If
>distilled water is ingested, the intestine has to add electrolytes to
>this water first, taking them from the body reserves. Since the body
>never eliminates fluid in form of "pure" water but always together
>with salts, adequate intake of electrolytes must be ensured. Ingestion
>of distilled water leads to the dilution of the electrolytes dissolved
>in the body water. Inadequate body water redistribution between
>compartments may compromise the function of vital organs. Symptoms at
>the very beginning of this condition include tiredness, weakness and
>headache; more severe symptoms are muscular cramps and impaired heart
>rate.
> ...
>Regular intake of low-mineral content water could be associated with
>the progressive ...changes discussed above, possibly without
>manifestation of symptoms or causal symptoms over the years.
>Nevertheless, severe acute damage, such as hyponatremic shock
>[water intoxication] or delirium, may occur following intense physical
>efforts and ingestion of several litres of low-mineral water (Basnyat
>et al. 2000).
> ...
>health problems were reported in mountain climbers who had prepared
>their beverages with melted snow ...not supplemented with necessary
>ions. A more severe course of such a condition coupled with brain
>oedema, convulsions and metabolic acidosis was reported in infants
>whose drinks had been prepared with distilled or low-mineral bottled
>water (CDC 1994).
> ...
>Although drinking water is not the major source of our calcium and
>magnesium intake, the health significance of supplemental intake of
>these elements from drinking water may outweigh its nutritional
>contribution... diets not deficient in terms of the quantity of
>calcium and magnesium, may not be able to fully compensate for the
>absence of calcium and, in particular, magnesium, in drinking water.
>[See also below section on how cooking with distilled water causes
>losses from food.]... epidemiological studies in many countries...
>have reported that soft water (i.e., water low in calcium and
>magnesium) and water low in magnesium is associated with increased
>morbidity and mortality from cardiovascular disease (CVD) compared
>to hard water and water high in magnesium.
> ...
>Recent studies also suggest that the intake of soft water, i.e. water
>low in calcium, may be associated with higher risk of fracture in
>children (Verd Vallespir et al. 1992), certain neurodegenerative
>diseases (Jacqmin et al. 1994), pre-term birth and low weight at birth
>(Yang et al. 2002) and some types of cancer (Yang et al. 1997; Yang et
>al. 1998). In addition to an increased risk of sudden death (Eisenberg
>1992; Bernardi et al. 1995; Garzon and Eisenberg 1998), the intake of
>water low in magnesium seems to be associated with a higher risk of
>motor neuronal disease (Iwami et al. 1994), pregnancy disorders
>(so-called preeclampsia) (Melles & Kiss 1992), and some types of
>cancer (Yang et al. 1999a; Yang et al. 1999b; Yang et al. 1999c;
>Yang et al. 2000).
> ...
>animals given water dosed with 5 mg/l of calcium exhibited
>[impairment] in thyroidal and other associated functions compared to
>the animals given the two higher doses of calcium.
> ...
>While the effects of most chemicals commonly found in drinking water
>manifest themselves after long exposure, the effects of calcium and,
>in particular, those of magnesium on the cardiovascular system are
>believed to [be rapid] Only a few months exposure may be sufficient
>[to cause health troubles] Illustrative of such short-term exposures
>are cases in the Czech and Slovak populations who began using reverse
>osmosis-based systems for final treatment of drinking water at their
>home taps...Within several weeks or months various health complaints
>suggestive of acute magnesium (and possibly calcium) deficiency were
>reported (NIPH
>2003). Among these complaints were cardiovascular disorders,
>tiredness, weakness or muscular cramps. These are essentially the same
>symptoms listed in the warning of the German Society for Nutrition.
> ...
>Although drinking water, with some rare exceptions, is not the major
>source of essential elements for humans, its contribution may be
>important for several reasons. The modern diet ...may not be an
>adequate source of minerals and microelements. In the case of
>borderline deficiency of a given element, even the relatively low
>intake of the element with drinking water may play a relevant
>protective role. This is because the elements are usually present in
>water as free ions and therefore, are more readily absorbed from water
>compared to food where they are mostly bound to other substances.
>Animal studies are also illustrative of the significance of
>microquantities of some elements present in water. For instance,
>Kondratyuk (1989) reported that a variation in the intake of
>microelements was associated with up to six- fold differences in
>their content in muscular tissue.
> ...
>Furthermore, a negative effect on the blood formation process was
>found to be associated with non-supplemented demineralised water...
>as much as 19% lower in the animals that received non-supplemented
>demineralised water compared to that in animals given tap water.
> ...
>Recent epidemiological studies of an ecologic design among Russian
>populations supplied with water varying in TDS suggest that low-
>mineral drinking water may be a risk factor for hypertension and
>coronary heart disease, gastric and duodenal ulcers, chronic
>gastritis, goitre, pregnancy complications and several complications
>in newborns and infants, including jaundice, anemia, fractures and
>growth disorders (Mudryi 1999).
> ...
>The population of the area supplied with water lower in minerals
>showed higher incidence rates of goiter, hypertension, ischemic heart
>disease, gastric and duodenal ulcers, chronic gastritis, cholecystitis
>and nephritis. Children living in this area exhibited slower physical
>development and more growth abnormalities, pregnant women suffered
>more frequently from edema and anemia. Newborns of this area showed
>higher morbidity.
> ...
>When used for cooking, soft water was found to cause substantial
>losses of all essential elements from food (vegetables, meat,
>cereals). Such losses may reach up to 60 % for magnesium and calcium
>or even more for some other microelements (e.g., copper 66 %,
>manganese 70 %, cobalt 86 %). In contrast, when hard water is used for
>cooking, the loss of these elements is much lower, and in some cases,
>an even higher calcium content was reported in food as a result of
>cooking (WHO 1978; Haring and Van Delft 1981; Oh et al. 1986; Durlach
>1988).
> ...
>Low-mineralized water is unstable and therefore, highly aggressive to
>materials with which it comes into contact. Such water more readily
>absorbs metals and some organic substances from pipes, coatings,
>storage tanks and containers, hose lines and fittings, being incapable
>of forming low- absorbable complexes with some toxic substances and
>thus reducing their negative effects
> ...
>Calcium and, to a lesser extent, magnesium in water and food are known
>to have antitoxic activity. They can help prevent the absorption of
>some toxic elements such as lead and cadmium from the intestine into
>the blood, either via direct reaction leading to formation of an
>unabsorbable compound or via competition for binding sites (Thompson
>1970; Levander 1977; Oehme 1979; Hopps and Feder 1986; Nadeenko et al.
>1987; Durlach et al. 1989; Plitman et al. 1989).
> ...
>The Czech National Institute of Public Health (NIPH, 2003) in Prague
>has tested the safety of products intended for contact with drinking
>water and found that the pressure tanks of the reverse osmosis units
>are prone to bacterial re-growth.

END QUOTED SECTIONS but there is a LOT more in there.

[Posted in FML 6554]