galvanized pipes - when to replace

[Peter Grote]

I am starting to purchase SFR homes to buy and hold. The homes I'm getting tend to be older 1900-1950 and so have galvanized pipes. What rule of thumb do people tend to use for when to replace them? when something's leaking? or when the hot water flow is becoming too slow? or when it's convenient because you're doing other rehab anyway? and then do a little at a time or all at once? thanks

[JD Martin]

All of the above.

If I am doing a rehab and we have easy access to them, and it doesn't cause a major production, we swap them out, usually for PEX but sometimes PVC/CPVC. Other times, if they are in difficult areas and the flow is good and not badly discolored or washing sediment into the basins, we will only do the main trunk line but leave the subsidiary lines. Occasionally, we don't mess with them at all if they look relatively clean inside if we've had a valve or tee off. If we make a repair on anything we don't put any galvanized fittings back as a rule. 

Most of the time we find that replacing the main trunk lines, if nothing else, and upsizing those lines makes a major difference in any flow problems. On the other hand, if your main service line from the street to the house is galvanized, and badly corroded, hardly anything you do in the house will make any difference.