Drinking water quality requirements focus mainly on removing hazardous substances from the water supply, making it safe to drink and appropriate for livestock use. However, there is a concern that high mineral content in water may affect the drinking behavior of heifer calves, which may affect health and performance. In South Dakota, the primary water sources for agricultural use are surface or groundwater. Water quality varies between different regions of the state; in the eastern part of the state, the water is classified as "hard water" and calcium is the primary mineral found in the water. Our objective was to determine the water intake and drinking preference of heifer calves offered water treated with a reverse osmosis system (ROW), water treated by a municipal city water treatment plant (TW), and local untreated well water (UWW). Six Holstein heifer calves (100 ± 6.5 d of age; 137 ± 5.9 kg of body weight) were used in a sequential elimination study. The calves were kept in individual pens (1.5 × 3 m) and fed similar pellet and grass hay rations. Three troughs (14 L) of water were provided for each heifer calf and refreshed 3 times per day. Three water types were randomly assigned to the troughs, and an extra trough on each side was left empty to avoid preferential behavior by location. Throughout the 8-d experiment period, the intake of each type of water by each calf was measured. During the study adaptation phase, heifer calves were given TW for 3 d to establish baseline intake. During phase 1, all 3 water types were offered for 3 d. The most-consumed water of each heifer calf was removed after intake data were collected. During phase 2, the remaining 2 water types were offered for 2 d. Water preference ranking by heifer calf was determined based on intake amounts. Kendall's coefficient of concordance (W) was calculated to evaluate the agreement of preference among the heifer calves. The total average water intake was 16.0 ± 2.14, 15.8 ± 1.95, and 14.9 ± 2.21 kg/d for the adaptation phase, phase 1, and phase 2, respectively. During phase 1, average intake was 7.10 ± 3.97, 5.10 ± 3.59, and 3.55 ± 4.89 kg/d for ROW, TW, and UWW, respectively. Three heifer calves preferred ROW first and TW second. Two heifer calves selected TW first and ROW second. One heifer calf chose UWW first and was a potential outlier in the group for taste preference. Average preference rankings were 1.67, 1.83, and 2.50 for ROW, TW, and UWW, with lower numbers indicating greater preference. Overall, most of the heifer calves in the trial showed similar preferences (W = 0.53), meaning that when one heifer calf had a preference for a particular water type, there was a trend for all the calves to prefer that water type. Results showed that the calves slightly preferred ROW over TW, and preferred both ROW and TW over UWW, with greater consumption of ROW when all 3 water types were offered.
