Hate to sound repetitive here - but you've got to forget the tap water! No matter how ya' cut it - tap water would be a bad decision to make! It's the fast, cheap and easy way in the short term but in the long term - it'll come back and bite ya' real hard! You need to purchase RO/DI water or buy yourself a unit - as a result your tankmates will be living in a more stable tank environment, there will be less problems and it'll actually be less expensive.
If you can mangage to hook up a RO/DI unit directly to your kitchen sink tap, I've seen this - you are good to go. But you shouldn't use tap water (water that comes directly out of any tap) and proceed to put that water straight into your tank. That would be a Big No-No!
"I live in Canada.. I am not sure of the water quality.. but there is a very reputable dealer.. (not a franchise) he was saying that the water should be ok to use.."
Doesn't matter where you live, chances are that it will not be good for a number of reasons! As far as what this reputable dealer said - do you mean lsf dealer or a water utility provider . . . either way you cannot take their advise - it sounds as though they really have no clue about the needs of a reef tank and how critical it is to use proper water. If it's a lfs owner saying this, I'd be very cautious of any other advise he gives if he is advising that the water is o.k. to use in a reef tank! If it's the water utility provider saying it's o.k. to use - then I'm going to assume this person is talking about the drinkability of the water. However, I'd question that as well - I would never drink from a local or municipal tap anyways - I stick with bottled water!
If it sounds like we're coming down hard on you - it's because we are! Those of us have seen hundreds of people make this mistake (probably even ourselves

) and suffer the consequences!

We do not want you to have to experience it as well!