Placement: softener before all fixtures, Brita filter after
Install the whole-home softener at the main cold water supply line entry point, before any distribution to the kitchen. The Brita pitcher continues to operate downstream of the softener -- it fills from the kitchen faucet, which now delivers softened cold water. The Brita filter then removes any residual taste from the sodium added during softening and polishes the water for drinking. This sequence (soften at main line, filter at point-of-use) provides both scale protection and optimized drinking water quality.
Impact of softened water on Brita filter life
Softened water increases Brita filter life measurably. The Brita Longlast filter (120-gallon rating) is rated in moderately hard tap water. In softened water (0-3 GPG), the filter reaches its 120-gallon life without the sediment and mineral fouling that occurs in hard water. Users who switch to softened source water for their Brita pitcher typically find filters last 10-20% longer than in hard water areas. The electronic indicator is time-based and does not reflect this extended life -- monitor taste and odor changes as a secondary indicator.
Sodium in softened water and Brita filtration
Ion exchange softeners add sodium to water in an amount proportional to the hardness removed. A 20 GPG hard water source softened to 0 GPG adds approximately 200-300 mg/L of sodium to the water. The EPA advisory level for sodium in drinking water is 20 mg/L (for taste) -- softened water often exceeds this advisory level in hard water areas. A Brita carbon filter does NOT remove sodium. If sodium content in drinking water is a concern (low-sodium diet, hypertension): (1) Install a point-of-use reverse osmosis system under the kitchen sink for drinking water (RO removes 95-99% of sodium), or (2) Use a potassium chloride (KCl) regenerant in the softener instead of sodium chloride -- KCl delivers potassium (not sodium) to the softened water, which has different dietary implications.