This report outlines the results of a telephone survey of mandated rainwater tank users in South East Queensland (SEQ) undertaken to establish baseline physical, demographic and behavioural factors influencing the implementation of mandated rainwater tanks in detached dwellings, as per the Queensland Development Code (QDC) Part MP 4.2. Under this development code, all detached dwellings in SEQ are required to save 70 kilolitres/household/year (kL/hh/yr) of mains potable water through the use of alternative water sources such as that obtained from household or communal rainwater tanks, greywater treatment systems, dual reticulation from recycled water and stormwater reuse.This report on the baseline characteristics constitutes Phase 1 of a wider research project investigating the physical (set-up) and socio-demographic factors influencing the use of rainwater tank water by individual households with mandated rainwater tanks in SEQ. In the broader research project, the actual use of rainwater tank water is estimate using water billing records. Tank design and governance and management issues in achieving and maintaining optimal mains water savings through rainwater use are also being considered.