Twin Impeller Shower Pumps for Hot and Cold supplies are ideal for any homes that might be suffering from low hot and cold water pressure. You might notice this in your morning showers as a bit of a dribble rather than a powerful spray. We split our twin impeller shower booster pumps into two categories, one for positive head and one for negative head. This may sound confusing but it’s really quite straightforward; positive head pumps work where the cold water storage tank outlet is higher than the outlet in your bathroom, this is generally the norm as most storage tanks are fitting in the loft. Negative head shower pumps are for when the cold water storage tank outlet is lower than the outlet you’re pumping to.