# Answer to Puzzle #26: Gas, Water, Electric to 3 Houses

26. A man has built three houses. Nearby there are gas water and electric plants. The man wishes to connect all three houses to each of the gas, water and electricity supplies.

Unfortunately the pipes and cables must not cross each other. How would you connect each of the 3 houses to each of the gas, water and electricity supplies?

This puzzle was also e-mailed to me through this website. I receive it once or twice a month so I thought it was about time I wrote out the answer. Unlike most of the problems on my site there is something of a trick to this one, and it's not exactly 'quant'...

Firstly, lets be sure we're clear of the layout:

Now it's just a matter of connecting up all the houses with all the suppliers...

Most people will get as far as connecting up 2 of the houses with three of the suppliers, and one of the houses with only two... At this point, unless you can see the trick, you get stuck.

click to enlarge

So the trick now is to connect the final supplier to the final house.

In this case this is done by passing the gas supply to the second house through the first house and so not crosing any of the other pipes and cables.

click to enlarge

Easy when you know how ;)

NB- Whilst I've said that feedback is always welcome, I'm not desperately keen to receive abuse over this answer. The email below is maybe at the extreme end but it is not completely atypical.
Your answer is not correct. Your proposed solution is considered "cheating". The puzzle is not solvable. Would you want someone else's water, gas, or electric line running through your house? I don't think so. You should remove your proposed solution or at least remove your smug comment "easy when you know how" and replace it with a statement that the answer you proposed is not correct.
– Kathryn Brandon
As I told Kathryn my answer is correct, it is an answer to the question that I asked.

It may not be the correct answer to some other question that Kathryn Brandon thought I should have asked, but it answers my question just fine. And as for whether I'd want someone else's electric line running through my house... couldn't care less. Further I have been informed that this does actually happen.

© Nigel Coldwell 2004 -  – The questions on this site may be reproduced without further permission, I do not claim copyright over them. The answers are mine and may not be reproduced without my expressed prior consent. Please inquire using the link at the top of the page. Secure version of this page.

PayPal
I always think it's arrogant to add a donate button, but it has been requested. If I help you get a job though, you could buy me a pint! - nigel