1.3 Secondary drinking water regulation [5].
| Chemicals | SDWR |
| Aluminum | 0.05–0.2 mg/l |
| Chloride | 250 mg/l |
| Color | 15 color units |
| Copper | 1.0 mg/l |
| Corrosivity | Non‐corrosive |
| Fluoride | 2.0 mg/l |
| Foaming agents | 0.5 mg/l |
| Iron | 0.3 mg/l |
| Manganese | 0.05 mg/l |
| Odor | Three threshold odor numbers |
| pH | 6.5–8.5 |
| Silver | 0.1 mg/l |
| Sulfate | 250 mg/l |
| Total dissolved solids (TDS) | 500 mg/l |
| Zinc | 5 mg/l |
Tables 1.3 and 1.4 show the 2018 Drinking Water Standards and Health Advisories, Secondary Drinking Water Regulations.
Table 1.4 WHO standards for potable water [5].
| Constitutes | Concentration (ppm) | |
| Limited values | Max allowed values | |
| Total dissolved salts (TDS) | 500 | 1500 |
| Cl | 200 | 600 |
| SO42+ | 200 | 400 |
| Ca2+ | 75 | 100 |
| Mg2+ | 30 | 150 |
| F− | 0.7 | 1.7 |
| NO3− | <50 | 100 |
| Cu2+ | 0.05 | 1.5 |
| Fe3+ | 0.10 | 1.0 |
| NaCl | 250 | — |
| pH | 7–8 | 6.5–9 |
Table 1.5 Thermo‐physical properties of typical seawater at 40 000 ppm and 20 °C.
| Density | 1.0288 kg/m3 |
| Specific heat capacity | 3.973 kJ/(kg °C) |
| Boiling point elevation, at 20 °C | 0.344 K |
| Boiling point elevation, at 90 °C | 0.565 K |
| Thermal conductivity | 0.601 W/(m K) |
| Dynamic viscosity | 1.089 × 10−3 kg/(m2 s) |
| Kinematic viscosity | 10.58 × 10−7 m2/s |
| Latent heat of vaporization | 2355.4 kJ/kg |
1.6.2 Seawater
Table 1.5 shows thermo‐physical properties of standard seawater at 40 000 ppm and 25 °C.
Note that the comprehensive thermo‐physical properties of seawater as a function of temperature and salinity are presented in Appendix A.
The major six elements that comprise about 99% of seawater are chlorine (Cl−), sodium (Na+), sulfate (SO42−), magnesium (Mg+2), calcium (Ca+2), and potassium (K+), and standard seawater composition at 35 000 ppm are presented in Table 1.6.
Table 1.6 Standard seawater composition at salinity equal to ≈35 000 ppm.
| Chemical ion | Concentration (ppm) | Valence | Total salt content (%) | mmol/kg | Molecular weight |
| Chlorine Cl− | 19 345 | −1 | 55.03 | 546 | 35.453 |
| Sodium Na+ | 10 752 | +1 | 30.59 | 468 | 22.990 |
| Sulfate SO42− | 2701 | −2 | 7.68 | 28.1 | 96.062 |
| Magnesium Mg2+ | 1295 | +2 | 3.68 | 53.3 | 24.305 |
| Calcium Ca2+ | 416 | +2 | 1.18 | 10.4 |
