Step one: Start with a habitat that is familiar to the Gremlin. Somewhere it has lived before. The more frequent it's previous infestations the better. Three or more previous visits is best.
Step two: Make sure no expense has been spared in eliminating the previous Pipe Gremlins. They like a challenge. The more "impossible" it is for them to return, the better the chances.
Step three: After you have managed to exterminate a Pipe Gremlin, wait. Chances are he will be back. Again and again. And again.
Step four: It is helpful if another Pipe Gremlin has already established itself nearby. For example, if you have one living in the drain of your washing machine. Despite the fact that you have cleverly subverted him with the hose out the window trick... (Yes, our neighbors love us! I do have some hope that they are too distracted by the house down the street painted like a clown tent to notice us.) Despite that clever trick, you know he is still there lurking. He is wishing for a friend. Because once you get two Pipe Gremlins you will have many more Pipe Gremlins. Think of this habitat as their nesting ground.
Step five: After you have waited a ridiculously overcautious length of time with dressers in hallways and children sleeping crammed into your bedroom finally begin the process of reclaiming your space. Do this cautiously at first. Begin by taking boxes of toys back into the room and allowing your children to sleep on the floor. Do not get over excited. Keep items light so that they can be easily moved back out at the slightest sign of a Pipe Gremlin attack.
Step six: Wait some more.
Step seven: When you have finally waited longer than any other human being on the planet would wait, finally decide it's time. Start by bringing in a heavy bunk bed that has to be disassembled and driven 5 hours in two different vehicles then reassembled in the room. Make sure that this piece of furniture can not be easily removed without taking it entirely apart.
Step eight: Continue to move larger furniture back into the room, like those two dressers that have been in your way for over a year. Organize and decorate the room. Because there is absolutely no way. No way the Pipe Gremlins would dare to rear their ugly heads after all that is accomplished.
Would never happen in a million years.
Step nine: Put your daughter in real underwear. (Just go with me on this. I promise it will make sense in a second.)
Step ten: After a long day, finally tuck the kids into their lovely bed. As you walk out of the room step in a puddle. Ask your daughter if she peed on the floor. She will happily confess. Give your daughter a little lecture about the need to tell you if she pees on the floor. Then realize that is a lot of pee. In fact the entire concrete slab under the flooring seems to be soaked. Realize she is a bit too small to have done all that in one day. Cross your fingers that she has been filling one of her little teapots up with water and dumping it on the floor which is a favorite game of hers.
Step eleven: Check the water meter for spinning. Establish that you do in fact have a leak. In the house.
Success. The Pipe Gremlins are back again.
Step twelve: I'll be needing a bottle of Tequila...