Every time when one of the numerous volcanoes (mount Agung, Merapi)  is erupting Nazava gets a lot of questions about volcanic ash in drinking water and how Nazava water filters can help getting save drinking water.

 Summary

• Elements in volcanic ash that dissolve into drinking water are not considered a health risk except for flouride
• During a volcanic eruption do not use rainwater as a source for your drinking water
• Ground water is least effected by volcanic ash deposition and is the recommended water source
• Nazava water filters are very effective in removing bacteria common in ground water and can help preventing disease outbreaks during a volcanic disaster.

Harmful toxins in volcanic ash

Ash will cause  Calcium (Ca), Sodium (Na)  Magnesium (Mg)  Potasium (K),  Fluoride  (F) and Sulfate (SO₄) levels to rise in surface water. Ground water will be less affected.  These chemicals occur naturally at significant concentrations in most surface and ground waters.  These elements may impart a metallic taste to water, and may produce red, brown or black staining of whiteware, but are not considered a health risk when consumed during a short term (say 6 months.)  These elements will be washed away with rainwater which means long term exposure is unlikely. Volcanic ashfalls are not known to have caused problems in water supplies for toxic trace elements such as mercury (Hg) and lead (Pb) which occur at very low levels in ash leachates.  Nazava water filters are effective in removing small elements of mercury and lead.

(source Wikipedia, , Stewart et al, 2007)

Ground water

Ground water is unlikely to be much affected by ash deposition because the elements in the water will be diluted and filtered or absorbed by soil particles.  Because chemical elements related to ash fall will cause the taste of the water before causing a health risk, taste is a very good indicator of pollution. If the taste of ground water is still “strange” after 3 months after the eruption, we recommend doing a chemical analysis of the water source.

Because ground water from shallow sources is often contaminated with bacteria, a Nazava water filter is needed to make the water potable (by removing the bacteria). Please note that chlorine will not work because it will be bound to the volcanic ashes.

Rainwater

Rainwater can contain high amount of ashes especially when collected through roofs.   Nazava water filters will improve the water quality by reducing turbidity, bacteria and neutralizing pH.  However, because of the high concentration of volcanic ash in rainwater, it is not recommended using rainwater during a volcanic eruption.

Surface water

Typical effects of ash fall on the quality of available water sources. 

Turbidity	Ash suspended in water will increase turbidity in lakes, reservoirs, rivers and stream. Very fine ash will settle slowly, and residual turbidity may remain in standing water bodies. In streams, ash may continue to be mobilised by rainfall events, and lahars may be a hazard in some regions. Turbidity will be fully filtered out by Nazava water filters
Acidity (pH)	Fresh ashfall commonly has an acidic surface coating. This may cause a slight depression of pH (not usually below pH 6.5) in low-alkalinity surface waters. Nazava water filters will slightly increase pH of the water so that after filtration the pH will be close to neutral (7).
Potentially toxic elements	Fresh ash has a surface coating of soluble salts that are rapidly released on contact with water. The most abundant soluble elements are typically Calcium, Sodium, Potasium, Magnesium, Aluminum, Sulfate and Flouride. Compositional changes depend on the depth of ashfall and its ‘cargo’ of water-soluble elements; the area of the catchment and volume available for dilution; and the pre-existing composition of the water body. In rivers and streams, there will be a short-lived pulse of dissolved constituents In lakes and reservoirs, the volume is usually large enough that changes in composition are not discernible The constituents most likely to be elevated above background levels in natural waters are Fe, Al and Mn, because these are normally present at very low levels. Thus, water is likely to become unpalatable due to discolorations or a metallic taste before it becomes a health hazard. These elements will not be filtered out with a Nazava water filter. Therefore, if the water tastes very salty/ steely, we recommend using another source (e.g. ground water)

(source USGS)