Water provide in lorry to factory is come under service tax

Dear all first thanks in advance. we are providing water procure from outside to factory .in this we are charging service for the providing of water .but our customer deny to pay the service tax for that.in this our view is other than negative list all are under service tax based on that we charging st.but customer says water coming under the goods .kindly any one clear that we are eligible to collect the service tax from customer This most urgent.