A system comprising a well drilled into an underground formation comprising hydrocarbons; a water supply; a steam production facility, the steam production facility comprising a filter to remove at least 80% of a quantity of divalent cations in the water supply; an exchange resin to remove at least 80% of a quantity of divalent cations in a filtered water stream that has already passed through the filter; a steam injection facility connected to the well and the steam production facility, adapted to inject the steam into the well.