TL;DR: The water generated from our atmospheric water generator was sent to an EPA-certified laboratory for testing. It was tested for pH (acidity/alkalinity), turbidity (cloudiness), metal content, mineral content, and bacterial contamination. So far, it looks good, but we need to run more tests!
You can view the designs for BlueIce Alpha on GitHub.
We generated water from the atmosphere and flushed the filtration system with the generated water for an hour. Next, we shut off the effluent spigot and allowed the reverse osmosis filtered water to collect in the pressurized collection tank, a component provided by the filtration system. Samples were collected to test for pH, turbidity, metals, minerals, and bacteria. Once collected, the samples were stored in a cooler with a frozen ice pack for preservation during transport to the laboratory.
Effluent: 9.10
pH is a measure of the acidity of the water (defined as the negative logarithm of the concentration of hydronium ions in moles per liter).0 The higher the pH, the more basic the water. Solutions that are neutral have a pH of 7. Our water was tested at 6.67 prior to remineralization (Test 1), and found to be 9.10 following remineralization (Test 0). The remineralization filter changes the pH of the water from 6.67 to 9.10 through the addition of calcium, magnesium, sodium, and potassium.1
pH does not have a MCL (Maximum Contaminant Level) defined in the EPA’s (Environmental Protection Agency) NPDWRs (National Primary Drinking Water Regulations),2 but does have a SMCL (Secondary Maximum Contaminant Level) defined in the NSDWRs (National Secondary Drinking Water Regulations, which are non-mandatory guidelines for aesthetics like taste, color, and odor) at 6.5 — 8.5.3
The pH of the water is safe but is outside the range of optimal guidelines. It is slightly basic. There are actually alkaline waters available that are touted as healthy, tho.
[0]: Wikipedia - pH
[1]: iSpring #RCC7AK-UV 7-stage 75 GPD Reverse Osmosis UV Filter System
[2]: EPA - National Primary Drinking Water Regulations
[3]: EPA - National Secondary Drinking Water Regulations
Effluent: 1.96 NTU-7.07 NTU
Turbidity is a measure of the cloudiness of the water, measured in units called NTUs (Nephelometric Turbidity Unit) and is a key test for water quality. 1.96 NTU exceeds the 1 NTU limit specified in the NPDWRs.0 Turbidity can be caused by a number of things,1 many of which would raise caution in drinking water, so further experimentation was required. We identified the source as the remineralization filter in a later test (Test 1), eliminating concern over any dangerous sources of turbidity.
1.96 NTU is too high, and warrants further testing
[0]: EPA - National Primary Drinking Water Regulations
[1]: Wikipedia - Turbidity
Reporting Limit: 0.005 mg/L
Aluminum: 0.013 mg/L
Iron: 0.010 mg/L
It is important to measure the concentrations of various metals in drinking water, as they can have adverse biological effects. The concentrations of aluminum and iron present in the filtered water are both below the concentrations mentioned by the EPA and the WHO (World Health Organization).0,1
Aluminum and iron do not have MCLs defined in the EPA’s NPDWRs, but do have defined SMCLs in the NSDWRs, and are not considered a risk to human health at the SMCLs. The SMCL for aluminum is 0.05 — 0.2 mg/L, and the SMCL for iron is 0.3 mg/L.2
The WHO guidelines mention that aluminum might be present at 0.1 — 0.2 mg/L in water supplied from treatment plants, and iron might be present in natural fresh waters at levels of 0.5 — 50 mg/L.1 The guidelines also mention an iron concentration of 2 mg/L, a 10% allocation of the 1983 JECFA (Joint FAO/WHO Expert Committee on Food Additives) established PMTDI (Provisional Maximum Tolerable Daily Intake) of 0.8 mg/kg body weight.1
The aluminum and iron levels in the water are safe.
[0]: EPA - National Primary Drinking Water Regulations
[1, page 382]: Guidelines for Drinking-water Quality, 4th Edition
[2]: EPA - National Secondary Drinking Water Regulations
Reporting Limit: 0.005 mg/L
Calcium: 5.012 mg/L
Potassium: 0.214 mg/L
Sodium: 0.502 mg/L
Drinking a large amount of perfectly pure water devoid of any salts or minerals is not advised. It is important that water contains osmolytes, as your body uses these minerals for cellular functions.0 These osmolytes typically consist of calcium, potassium, and sodium salts. In addition to affecting the osmotic strength of the water, they can also affect taste.
Calcium content in bottled water available in North America has been found to range from 1 — 240 mg/L, and 0 — 546 mg/L for bottled water available in Europe.2
Since the recommended daily requirement for potassium is greater than 3000 mg, the WHO does not consider it necessary to establish a health-based guideline value for potassium in drinking water.3
Sodium salts are typically found in potable water at concentrations less than 20 mg/L, as well as most foods, therefore no health-based guideline is proposed by the WHO.4
The mineral content of the water following remineralization is appropriate.
[0]: WHO - Health risks from drinking demineralised water
[1, page 45]: Calcium and magnesium in drinking-water: Public health significance
[2, page 412]: Guidelines for Drinking-water Quality, 4th Edition
[3, page 416]: Guidelines for Drinking-water Quality, 4th Edition
Total Coliforms / 100mL: Absent
E.Coli / 100mL: Absent
From this test, the water is not contaminated with bacteria. The reverse osmosis and UV filters should eliminate any bacterial contamination, so this result is as expected.
We hypothesized the remineralization filter was the most likely source of turbidity, and designed an experiment to test this. We ran the generated water through the reverse osmosis system, and collected samples immediately before the alkaline (remineralization) filter, and immediately after. The samples collected were for influent pH and turbidity, and effluent turbidity (we already had effluent pH from test 0).
Influent: 6.67
This is within the range of 6.5 — 8.5 defined in the EPA’s NSDWRs.0
It seems alright.
[0]: EPA - National Secondary Drinking Water Regulations
Influent: 0.26 NTU Effluent: 7.07 NTU
0.26 NTU is below the 1 NTU limit specified in the EPA’s NPDWRs.0
Many of the possible sources of turbidity would make water unsafe to drink, but this experiment suggested the turbidity was caused by the remineralization filter. This eliminates concern over any dangerous sources of turbidity.
[0]: EPA - National Primary Drinking Water Regulations
We have a list of further tests we would like to run on the water, and water testing is expensive, but you can help! We have launched our Indiegogo campaign, and we’d love for you to be a part of this project.
VOCs (volatile organic compounds)
Non-Volatile Synthetic Organic Chemicals
Residual disinfectants and DBPs (Disinfection by-products)
Radioactivity
TDS (Total Dissolved Solids)
Trihalomethanes
Haloacetic acids
Organochlorine Pesticides
Chlorinated Phenoxy Acid Herbicides
SOCs (Synthetic Organic Chemicals)
Other heavy metals
…and more!