Respuesta :

180 * 365 = 65700 litres/year
65700 / 1000 = 65.7 m^3/year
0.9122 * 65.7 = £59.932 for water used
28.20 + 59.93 = £88.13 for water meter annually

£88.13 < £107 so yes, he should have a water meter.