Residential roof top water heaters are the most economical & effective solutions for heating water for heating water for domestic requirements. As a thumb rule, 150 liters per day are required for a family of 2 persons. This includes bathing and kitchen requirements. In case hot water is required for washing clothes, then is requirement is increased accordingly. For a pure solar water heater no electricity connection is required and no pumps are required. However, to cater for incessant rains for many days electrical element can be fixed in the system. This can heat water in case the solar collectors and not able to do so. Vatsalya Energy is an expert in this field as it has installed residential water heaters in varies terrains, states and different altitudes.