[secondfloor]

I have a second floor laundry and we have a new washer that really drains with some force. The problem is that the drain line backs up from the p trap because the gravity drain is not fast enough and it backs up from the trap...about three feet down inside the wall, until it is running down the wall and flooding the room. Is there a sealed cap and hose that contains the pressurized water?

 

[AllanJ]

You may not seal the washing machine hose onto the drain pipe; it must fit loosely. You may not splice onto the hose to extend it.

YOu can install a laundry tub that the machine empties into and then the water drains from the tub by gravity.

How fat is the drain pipe? Current code requires two inch pipe at least 18 inches up from the trap.

 

[LateralConcepts]

AllanJ is correct. It's either under-sized or partially clogged. It's a common problem with older plumbing. Newer washing machines have much more powerful pumps and discharge the water at a greater volume. Your existing piping can't handle it.

You'll need to either re-plumb it (up-size), or put in a laundry tub to accomodate as Allan mentioned. A laundry tub would be less intrusive and an easier project for a DIY'er.

I would first try snaking the drain with a 3/8" power snake. Also going forward, use a lint trap securely fastened to the washing machine discharge to help prevent future blockages.