since the family spends ten minutes on average per shower and there is 2.5 gallons spent per minute, 25 gallons are used per shower and with 4 shows per day, 100 gallons are used per day, so in 30 days they use 3,000 gallons of water, since water costs $1.50 per 1000 gallons, showering only costs them $4.50 per month