Major power utilities overcharged 380 users of electric water heaters by 1.45 million yen in fiscal 2001, the Ministry of Economy, Trade and Industry said Wednesday.
The cumulative total of the overcharges stands at 260 million yen since a discount system for electric water heaters started around 1984.
The ministry conducted a probe of about 250,000 users that started or renewed contracts for electric water heaters in fiscal 2001, which ended March 31.
Although the nation's 10 power utilities offer discount rates for such users, all of the firms made transactional errors in applying discount rates.
The utilities also overcharged about 630 other customers who should have been given discounts. Those overcharges totaled about 8.6 million yen for the year, according to the ministry.
Later this week, the ministry will instruct utilities to improve their monitoring systems and help raise user awareness of contracts, a ministry official said.