I have very specific practical question. Which way a pipe will last the longest and less corrosion will appear inside (internally) the pipe while it last? 1 I have one shower water IRON pipe, the question is it good idea to leave water inside the shower pipe after each use (use shower almost every other day) or let it out (through the faucet) ? 2 I have another shower water COPPER pipe, the question is it good idea to leave water inside the shower pipe after each use (use shower almost every other day) or let it out (through the faucet) ? Thanks a lot
The water can stand in the shower riser between showers without ill effect, however dumping the water after each shower is also a common practice and results in little or no long term effects. Both are acceptable and common practice.
It depends mostly on the water. A mildly scaling water will put a thin , protective scale in the pipes; no corrosion problems. A soft acidic water ( rain or many river waters ) will cause some corrosion ; the copper is likely to last longer than you. Steel ( eg Sch.40 ) may require replacement in 20 years. Letting them empty and dry periodically probably does not accelerate the corrosion. A water softener would make the corrosion worse. Shower extensions in the US are usually brass -about the same corrosion as copper in this case.