you want to run 60 ft 6 in to the front of the house, to join with the existing house main to the street(there are PVC 4+6 Y joints) . If the existing house main is 6 in( usually a 4 in) that's ok; if it's 4 in, then you have to dig out from this joint to the street drain and replace with 6 in from the point of join to the street, since you can only go from small to bigger down the stream, not the other way around.
If the street main connection is smaller than 6 in then you have not such option.
you are talking about 2 guys 2 day's work for digging and recover, material cost about 250 dollars.
有个老房子，室内外的排水管道都要换PVC管。
若走前院，只需拐一个弯，但要经过水泥车道。若走后院，要拐三个弯，长度由约30尺变60尺，但全是泥土。
我猜走后院能省2K。只是不知道效果有多大差别，有哪些注意事项。这条排水管只承担4卧房的洗衣房和一个洗手间。我打算把这项工程分拆成几部分（挖地的和修墙的--要开墙，再单请一位换排水管的plumber)。我请过几家plumbing报价都过万，我想分拆工程可能能省一半钱，但心里不肯定我的方案都可行。
谢谢！
60 ft = 1.5ft drop. You have to be sure you can accommondate that.
however you have to make sure you can connect 6 inch with city main at the street.
you want to run 60 ft 6 in to the front of the house, to join with the existing house main to the street(there are PVC 4+6 Y joints) . If the existing house main is 6 in( usually a 4 in) that's ok; if it's 4 in, then you have to dig out from this joint to the street drain and replace with 6 in from the point of join to the street, since you can only go from small to bigger down the stream, not the other way around.
If the street main connection is smaller than 6 in then you have not such option.
you are talking about 2 guys 2 day's work for digging and recover, material cost about 250 dollars.
我需得自己承担后果，让别人按我说的做，才有人敢接活。
所以，要先摸清底细。
堵了，请plumber通开，同时看了管道内实情，发现车棚水泥地内下的一段管道比外面低，时间长了堵在那里（不是油脂，我们从不让油脂进水池）。
当时住进（买的全新装修）房子没几年，于是找了造房时的plumber来处理。他们不想我们去走保险之路（可能对他们生意有影响？），又请了别的plumber大拿来再次做管道探测。大拿对我们特友好同情，给了一份录像留底。并告诉造房plumber唯一修理办法是重铺车棚水泥地下面的管道（当然由他们负责全部费用）。
因为按原管道重铺要对整个车棚水泥地面和部分车道“刨肠破腹”，而且要和已有臭管道打交道。我提议（并经过先生同意）要求另开一路，而且两个拐弯处不要90度直角，做成斜线和45度的拐角，新管道斜着横穿车棚然后和车道并行一直做到市里的接口为止。这样虽然要多挖一段，但大多部分是泥土。所以plumber也同意了。最后长度大概60尺，是6"管径，2个半人做了4天左右。
里面塞满了泥沙。新的PVC都是4“的，不明白你干嘛要用6”的。我的长度不到20米，但也超过15米应该，两个湾，地有坡度，管道下坡，像susan说的，每个弯装了Cleanout。全部工程是贴着外墙做的，房后一小段因为是坡，得挖很深，师傅跳下去齐胸。老外的报价全部过2万，中国师傅1万多。目前情况良好，经历了两个雨季一个雪季。