Unless the water heater is made for a horizontal sidewall termination, it cannot be done. You might be able to put a vertical chimney outside and connect to it though. Call a gas tech or a plumber. If you do it wrong the thing might not vent properly, filling your house with CO.

I thought there had to be a certain amount of rise for every run in the pipe to make it work. Are you saying you can't run any pipe sideways (at a slight angle up)?

You can, however I do not know the ratio.

Your best bet is to consider changing over to a PowerVent-type HW heater, they are vented out through the wall using PVC pipe.

If you have a furnace (I'm assuming not) and were to keep using the B-vent, it would probably need to be sleeved or reduced in diameter, since it'll be carrying less exhaust. If you don't, you will have condensation issues.

If you can't get clear written directions on the regulations and how do install, consult a pro - you could easily gas yourself.

All I want to do it take a 90 degree pipe of the top of the gas wh and run a pipe about 10 feet sideways and out of the side of the house. I could have a rise of a foot over that 10 feet if I need to.

If that's acceptable, how do you run it through the side of the house and terminate it?

These are the rules in my Ontario:

8.14.2
Except for a special venting system with positive vent pressure, a vent shall extend not less than 2 ft
(600 mm) above the highest point where it passes through a flat roof of a building and not less than 2 ft
(600 mm) higher than any portion of a building within a horizontal distance of 10 ft (3 m).

8.14.4
A chimney shall extend not less than 3 ft (900 mm) above the highest point where it passes through the
roof of a building and not less than 2 ft (600 mm) higher than any portion of a building within a
horizontal distance of 10 ft (3 m).

8.14.5
Except for a special venting system with positive vent pressure, a vent passing through a pitched roof
shall extend above the highest point where it passes through a roof surface in accordance with Figure 8.1
and shall extend not less than 2 ft (600 mm) above any other obstruction within a horizontal distance of
10 ft (3 m).

8.14.6
A vent or chimney shall extend not less than 5 ft (1.5 m) in height above either the highest connected
appliance draft-hood outlet or flue collar except as provided in Clause 8.24.1.

8.14.12
A vent from an appliance shall not extend through an exterior wall and terminate adjacent to the exterior
wall unless
(a) the appliance is a direct-vent appliance;
(b) the appliance is intended for connection to a special venting system;
(c) the appliance and its complete vent assembly are specifically certified to be installed in this manner;
(d) the venting system is equipped with a certified power venter that complies with Clause 8.29.2; or
(e) the venting system is equipped with a certified power venter that complies with Clause 8.24.2.

Please get a qualified installer to find a remedy for you.

We just did this with a 12-year-old gas water heater, so it can definitely be done. You should check your local code for the specifics, though; they vary. In our city, it just had to meet the proper ratio of horizontal and vertical rise. Ours goes through the wall and up the side of the house, terminating just above the roof line. We hired a local HVAC firm to do the work, though, which was well worth it. Took them half a day. Would have taken me that long just to research how to do it properly!

Exactly. Terminate above the roofline. The OP wants to terminate out the sidewall, which likely cannot be done. Let us know what you did to resolve this.