The effect of urine dilution on the kinetics and equilibrium sorption of ammonium to two natural zeolites was investigated for undiluted urine and urine at dilution levels of 10% (v/v), 1% (v/v), and 0.1% (v/v). Ammonium and the inorganic cations potassium, sodium, magnesium, and calcium were measured to elucidate the chemical interactions during the sorption process. The results show that ammonium removal from urine was greatest at the undiluted level. This is a key finding because it illustrates the benefit of urine source separation and treatment rather than the treatment of dilute wastewater streams. The removal of ammonium from urine was comparable for clinoptilolite and chabazite. For both zeolites, sodium was exchanged for ammonium and potassium. Both magnesium and calcium concentrations remained relatively constant during the sorption process.