The number of people diagnosed with cholera in the country has risen to 39,806. The WHO earlier said up to 60,000 people could be infected in the worst-case scenario.
A total of 1,472 cases and 117 deaths were recorded on Tuesday.
About 11,000 cholera cases and 238 deaths have been recorded in the capital, Harare. Other major concentrations of the disease include Beitbridge on the South African border (4,275 cases and 134 deaths), Makonde in the southern part of the country (3,046 cases and 102 deaths) and Mudzi on the border with Mozambique (2,051 cases and 125 deaths).
The United Nations Children's Fund (UNICEF) estimates that 80% of people lack access to safe and clean water in Zimbabwe, which has in recent years become a focus of international concern over widespread human rights violations and a crumbling economy.
UNICEF has warned that the outbreak of cholera, which is spread by drinking contaminated water, could "get even worse due to a deteriorating sanitation system."