Just want to share our experience with some plumbing issues in relation to our kitchen sink and washing machine. Sometime last week we decided to do laundry for the first time at our new place. It was recommended that for new washing machines, one should do 1 full empty cycle first before actually loading clothes in. Luckily we did so because what we didn't know was that major plumbing issues were about to occur! About 15 mins into the washing cycle, I started to hear some bubbling noise coming from the kitchen sink area, which is odd since I was doing laundry, not washing the dishes! I hurried over to the sink and found soapy foaming water coming UP from under the sink and into it and the water started to rise in the sink. Got a shock of my life but managed to keep calm to avoid stressing the missus out. HAHA. Immediately went over to the washing machine and turned off the main water pipe for the washing machine before turning the washing machine off. After surveying the area, I realized that some areas under our kitchen cabinet had water coming up from under it, and some of the water made its way onto our kitchen floor. Spent some time clearing the soapy water and even then, it continued leaking for a while. Thereafter I smsed our contractor to come fix it promptly. To cut the long story short, what appeared to be the problem was that the kitchen sink and washing machine shared the same drainage pipe, so much so that when the water pressure for either builds up, the water takes the least path of resistance which is not necessarily down the drain, but up into the sink or up into the washing machine. The plumber has since come down and separated the drainage pipes into 2 separate ones, each serving either the sink or washing machine. Do take note of this when you are configuring the plumbing for your kitchen/yard area. Lesson learnt! +1 experience point.