Water head is actually water pressure. Generally, domestic tap water should be kept at more than ten meters to start the water heater normally. Your question can be roughly as follows: 1. What is the vertical distance between your water tower and the faucet (at least several meters)? 2. Try not to have too many elbows and valves in the pipeline between the water tower and your faucet (too many elbows and bad valves will consume a lot of water pressure). Don't seal the water tower, but ventilate with the outside.
Is only the shower small? You can talk about the above three questions, and I'll analyze them again.