In the work failure of the water supply network forecast in the selected city was prepared. Proposed methodology with the use of archive failure data from the period of 20 years was discussed. The first forecast was made using the time series method, with the ultimate achievement being a foreseen value for the damage intensity coefficient in 2017. The second forecast was made using the naive method. Forecast gives the opportunity to plan the work of remount teams, inventory and spare parts, inspection and remelting periods, optimal repair periods of other elements of the water supply network. Forecasts also allow to plan a long-term plan to renew the water supply network, eg according to the recommendations for the exchange of 2% of the network length per year, which results in the renewal of the entire network within 50 years.