  The Jiangmen Underground Neutrino Observatory is proposed to determine
neutrino mass hierarchy using a 20~ktonne liquid scintillator detector. Strict
radio-purity requirements have been put forward for all the components of the
detector. According to the MC simulation results, the radon dissolved in the
water Cherenkov detector should be below 200~mBq/m$^3$. Radium, the progenitor
of radon, should also be taken seriously into account. In order to measure the
radium concentration in water, a radium measurement system, which consists of a
radium extraction system, a radon emanation chamber and a radon concentration
measurement system, has been developed. In this paper, the updated radon
concentration in gas measurement system with a one-day-measurement sensitivity
of $\sim$5~mBq/m$^3$, the detail of the development of the radium concentration
in water measurement system with a sensitivity of $\sim$23~mBq/m$^3$ as well as
the measurement results of Daya Bay water samples will be presented.
