关于water pipes

很多买家看房子的时候都会问，这个房子的水管是铜管还是PB的。

一般来说，Polybutylene (简称PB)是一种类似塑料的材料，以其低廉的造价和容易安装，广泛的应用在于1978年到1995年左右建造的房子。 PB的水管有蓝色的，灰色的，还有黑色的。

怎么能看出来房子用的是铜管还是PB， 很多的home inspector也都会推辞让你去找专业的水管工(plumper）来看。 有一些signs你可以观察来确定水管的材质：

Exterior - Polybutylene underground water mains are usually blue, but may be gray or black (do not confuse black poly with polyethelene pipe). It is usually 1/2" or 1" in diameter, and it may be found entering your home through the basement wall or floor, concrete slab or coming up through your crawlspace; frequently it enters the home near the water heater. Your main shutoff valve is attached to the end of the water main. Also, you should check at the water meter that is located at the street, near the city water main. It is wise to check at both ends of the pipe because we have found cases where copper pipe enters the home, and poly pipe is at the water meter. Obviously, both pipes were used and connected somewhere underground.

Interior - Polybutylene used inside your home can be found near the water heater, running across the ceiling in unfinished basements, and coming out of the walls to feed sinks and toilets. Warning: In some regions of the country plumbers used copper "stub outs" where the pipe exits a wall to feed a fixture, so seeing copper here does not mean that you do not have poly. Any gray plastic pipe could be poly. Look at pipes near the water heater. See what kind of pipe runs across the ceiling in an unfinished basement. Check the pipe that comes out of walls to feed sinks and toilets. Many properties have a combination of copper and poly pipes.

为什么说PB管不好？

因为水的PH值可能偏酸或者偏碱，然后很多地方的水里含有oxidants， 会和PB管起一些反应，最后引起管子变脆。 整个水管系统就会慢慢的损坏。

买房子的时候，建议问清楚卖家和listing agent, 水管是不是PB的。 然后可以检查sink 下面，around 热水器， 看有没有灰色，黑色和蓝色的管子。 如果你不sure, ask your home inspector or plumber.