Access to safe drinking water and improved hygiene are important for reducing morbidity and mortality from diarrhea. We surveyed 330 pregnant women who participated in an antenatal clinic-based intervention in Malawi that promoted water treatment and hygiene through distribution of water storage containers, sodium hypochlorite water treatment solution, soap, and educational messages. Program participants were more likely to know correct water treatment procedures (62% versus 27%, P < 0.0001), chlorinate drinking water (61% versus 1%, P < 0.0001), demonstrate correct handwashing practices (68% versus 22%, P < 0.0001), and purchase water treatment solution after free distribution (32% versus 1%, P < 0.0001). Among participants, 72% had at least three antenatal visits, 76% delivered in a health facility, and 54% had a postnatal check. This antenatal-clinic-based program is an effective new strategy for promoting water treatment and hygiene behaviors among pregnant women. Participants had high use of antenatal, delivery, and postnatal services, which could improve maternal and child health.