If a unit is a m³ then 150 units is in the area of one year's use. Often it is calculated as 100 litres per person per day; however, you might use more in hot countries if shower more often like 2-3 times a day. So, 100 ltr. x 2 x 365 = 73,000 ltr. = 73 m³. In my home country I used about 100 m³ per year. Here in 'paradise' I don't have a meter, but get water by truck, in average we use about 125 m³ in a year for two — including refill of outdoor jacuzzi, laundry, and some light car wash — and sometimes a pair of guests, totalling may two month in a year. So, if a unit equals one cubic meter and you water bill for one mon th is in the area of 150 units, there must be some heavy leak somewhere. Note that a running toilet can consume a lot of water.