By that logic, let's all turn on every tap in the house. Drought averted!
We're fooled into believing water shortages are environmental problems we need to make sacrafices to prevent. But just paying more for more expensive, higher volume production or recylcing would work too. Eg Isreal.
But you are correct that they we're asking people to water their lawns once and a while. The difference here is that Ottawa gets its water from the Ottawa river which is a main tributary of the St-Laurent and is itself fed by a massive watershed starting about 7 hours north (funny thing, as you drive up highway 11 you will pass a sign that say "Now entering Arctic watershed").
Not to mention the fact that you don't live in one of the few places with abundant fresh water, even during a drought.