What can be removed from drinking water by Nazava Water Filters?

Summary

• All fresh water sources that are not chemically contaminated even when murky
• Water that is currently consumed after boiling can always be used as raw water
• Rain water can always be used
• Iron & Manganese are removed by 90% and 50 % respectively
• Inlet water may be very contaminated with bacteria

What water can be used

The Nazava water filter is designed to remove bacteria from water. However, it also makes murky water clear and removes some chemicals. Nazava is more effective in removing bacteria than boiling is so, a Nazava water filter can always be used to replace boiling.

Bacteria

The typical number of bacteria in ground water in Indonesia varies between 5 and 1000 MPN/100ml. 1000 MPN / 100 ml is the number of bacteria in a sewer.  Water which such number of bacteria will stink and can also not be used for bathing.  This amount of bacteria corresponds to 1000 turds (poos) per swimming pool or a bathtub filled with 1000 butt wipes (http://oasisdesign.net/water/quality/coliform.htm) .

Iron

Iron is a harmless element even in high concentrations (see WHO guideline). However, even at very small concentration (0.1 mg/l), because of that you might find rusty sedimentation/ stains at the bottom of your filter tank if you do not clean it regularly. The stains can be removed with Vixal, household vinegar or other acid based cleaning products.  Iron is removed reasonably well by the Nazava filter because it can be filtered out after it oxidizes.  If you have a high iron water source, it is best to let the iron settle down in a bucket for a day and then pour it into your filter.

Manganese

Manganese is a vital element, but the daily intake of it must be limited. Manganese is likely to be high in your water when you have black stains in your bathtub or sink. If you have those it is best to have your water tested. When manganese content is higher than 0.8 mg/l we do not recommend using the water for drinking and cooking. Nazava sells separate filters to remove Manganese content.  After some time, even with very low amounts of Manganese (starting from 0.05mg/l ) manganese might cause stains in the drinking water container and tap of the filter.  This is not a health risk and they can be removed with household vinegar or acid bases detergents like vinegar.

Hardness (calcium & magnesium carbonates)

Hardness is not a health risk. The WHO even proposes minimal amounts of those minerals  (see here and (http://www.who.int/water_sanitation_health/dwq/chemicals/hardness.pdf) .  The national guideline is based on taste. Hardness is reduced around 10% by Nazava filters . For that reason, intake water should not exceed 500 mg/l. This can be easily tested with a TDS meter.

TDS

TDS is the total of all dissolved solids in water.  TDS itself is not related to health. TDS is not reduced by Nazava filters so intake water should not exceed the guideline value of 500 mg/l.   TDS can be measured with a TDS meter or by tasting. From 400 mg/l and up the water will have a slightly salty taste. Therefore, if the water tastes fresh (not salty) TDS is likely to be below 500 mg/l.

Murkiness/ turbidity

Murky water will become clear however the murkier the water the slower filtration will be. For that reason, it is recommended to let the mud settle down first and /or prefilter the water with a cloth.  We have tested the filter with very turbid water with  279NTU. After filtration the water had a turbidity of 1.5NTU which is well below the WHO guideline of 5NTU.  You can find the report here. 

Humic acids

Humic Acids (peaty water, air gambut) cannot be filtered. However, if the water is pre-treated with PAC (readily available) and left to settle for 8-12 hours the humic substances will be removed from the water.

All other chemicals

The activated carbon in the filter will reduce amounts of organic compounds (like pesticides) and also chlorine. Because interactions are very complex, we cannot yet guarantee certain removal rates.  Also, we have never found high levels of other chemicals in raw water and our contacts at the Ministry of Health and ITB also report that the only issues regarding drinking water are bacteria, iron & manganese, and sea water intrusion (high TDS) and humic-acids. Arsenic has been reported in a few deep wells in South Sumatera. However, according the ministry of health arsenic contamination is rare out site of mining areas.  If people install a deep well, it is always recommended to do a full chemical test which is cheap compared to the costs of drilling such a well. If you are not sure about your well water, rain water is abundant in 90% of Indonesia.