Combine the water, coconut milk, and salt in a medium saucepan and heat over medium-high heat until the mixture starts to simmer. Add the rice and bring back to a low simmer. Cover the pot, reduce the heat to low, and cook undisturbed for about 15 minutes, until all the liquid has been absorbed. Turn off the heat and let the rice steam for another 5 to 10 minutes, until fully cooked and soft. Uncover, fluff, and toss in the lime zest and juice.