utility room

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A room used for keeping large typically household appliances, such as a washing machine and dryer, or for storing cleaning items, such as a mop, bucket, and broom.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A room that contains typically washing machine, tumble dryer, and other appliances which, in houses without such a room, would be in the kitchen or laundry.