Is it better to use tap water or not to use tap water for heating pipes of solar water heaters?

These two kinds of pipes have their own advantages and disadvantages. Heat pipes without running water cost more, so water heaters are more expensive. Tap water has low cost and cheap price. This is the advantage. Generally speaking, most water pipes are equipped with dripping solar water heaters, and heat pipes are generally equipped with pressure-bearing solar water heaters. These two kinds also have their own advantages and disadvantages. What are your main needs? Just buy what kind. Advantages of water drop type: low price and high utilization rate of hot water. Disadvantages: the water outlet pressure is small, the big shower can't be sprayed, and a pump is needed. The reverse side of the pressure-bearing type.