GNSS receivers and antennas are set up in Beijing to receive the second-level signals of the GNSS system. Data quality checks are conducted using software. Leveraging precise ephemeris data from the BeiDou Navigation Satellite System (BDS) B2b signal, real-time zenith total delay (ZTD) and precipitable water vapour (PWV) retrieval experiments are conducted using BDS Precise Point Positioning (PPP) techniques, single GPS, and their integrated solutions. These results are systematically compared against ZTD/PWV estimates derived from BDS/GPS dual-difference network solutions, radiosonde observations, and ERA5 reanalysis datasets. The results show that the average signal-to-noise ratio of the GNSS signal is greater than 35, and the multipath effect is better than 0.5 m, ensuring robust observational conditions for inversion modelling. Compared with the double-difference network solution, the average deviation of the tropospheric delay inversion based on BeiDou precise point positioning is 4.5 mm, the root mean square error is 9.94 mm, and the correlation coefficient is 90%. The corresponding PWV inversion average deviation is 0.35 mm, the root mean square error is 1.33 mm, and the correlation coefficient is 96%. Compared with radiosonde, the average deviation of the tropospheric delay inversion is 5.83 mm, the RMSE is 7.38 mm, and the correlation coefficient is 95.07%. The corresponding PWV inversion average deviation is 1.03 mm, the root mean square error is 1.72 mm, and the correlation coefficient is 94.45%. This indicates that the ZTD/PWV inversion technology derived from BDS makes single-system and single-point solutions possible. This method adopts a distributed computing strategy, avoiding the bandwidth and storage pressure of returning the solution data to the central station at the station end in the past, improving the real-time performance of water vapour solutions, and can represent the trend of water vapour change. It is of great significance for the monitoring and early warning of weather phenomena and meteorological disasters related to water vapour.