Twardość ogólna badanej wody wynosi 2,5 mval/l. Wartość ta wyrażona w mg CaCO₃/l wynosi <br><br> <table><tr><td colspan="6">Tabela. Jednostki twardości wody</td></tr><tr><th>Jednostka twardości</th><th>mmol/l</th><th>mval/l</th><th>mg CaCO3/l</th><th>°fstopień francuski</th><th>°nstopień niemiecki</th></tr><tr><td>1 mmol/l</td><td>1</td><td>2</td><td>100</td><td>10</td><td>5,6</td></tr><tr><td>1 mval/l</td><td>0,5</td><td>1</td><td>50</td><td>5,0</td><td>2,8</td></tr><tr><td>1 mg CaCO3/l</td><td>0,01</td><td>0,02</td><td>1</td><td>0,1</td><td>0,056</td></tr><tr><td>1 stopień francuski (°f)</td><td>0,1</td><td>0,2</td><td>10</td><td>1</td><td>0,56</td></tr><tr><td>1 stopień niemiecki (°n)</td><td>0,178</td><td>0,357</td><td>17,8</td><td>1,78</td><td>1</td></tr></table>

• A50,00 mg CaCO3/l
• B125,00 mg CaCO3/l
• C1,25 mg CaCO3/l
• D12,50 mg CaCO3/l