• 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

The typical number of bacteria in groundwater in Indonesia varies between 5 and 1000 MPN/100ml. 1000 MPN / 100 ml is the number of bacteria in a sewer. Water which a such a number of bacteria will stink and can also not be used for bathing. 

(http://oasisdesign.net/water/quality/coliform.htm) .

Iron is removed reasonably well (about 90%) by the Nazava Water Filter because it can be filtered out after it oxidizes. Iron is an essential essential element in human nutrition, however even at very small concentration (0.1 mg/l), you might find rusty sedimentation/ stains at the bottom of your filter tank if you do not clean it regularly. However, the stains can be removed with household cleaning products such as Vixal, vinegar or other acid based cleaning products. 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. See WHO guidelines for more information.

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 by around 10% by Nazava Water Filters. For that reason, intake of water should not exceed 500 mg/l. This can be easily tested with a TDS meter.

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.

TDS is the total of all dissolved solids in water. TDS itself is not related to health. TDS is not reduced by Nazava Water Filters so intake water should not exceed the guideline value of 300 mg/l. TDS can be measured with a TDS meter or by tasting.

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 pre-filter 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 (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.

Viruses themselves are too small to be removed by filtration. However, since viruses need to attach themselves to an organism to survive, it’s these organisms that get attached to particles and get removed by the ceramic filter. However, mcuh of any remaining viruses will be inactivated by the nano-silver in the Nazava Filter. See research from Park et al. for example. In addition activated silver has been shown to be effective against HIV, Murine norovirus 1 (MNV-1), and hepatitis.

To summarize, due to the combination of filtration and nano silver, our filters provide decent protection against viruses when using ground, tap, river, or rain water. However, if you suspect your water source has an extremely high viral load, we recommend using a different water source, otherwise you may need additional disinfection like chlorine.

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 the Bandung Institute of Technology (one of Indonesia’s leading universities) 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 Indoneisan 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.