Your RV's specific situation dictates the answer to this inquiry. Tankless water heaters without built-in pumps are an option if you have a large Class A motorhome with a working water pump. If so, you can save money. People with popup campers or small travel trailers may need an additional water pump to take advantage of the tankless water heaters' higher flow rate. Tankless water heaters are sold separately by several manufacturers. After that, you'll need a 12-Volt electric water pump, which you can connect. An accessory pump designed to work with the tankless water heater is available with many of these units. You may even be able to get them all together in one place!