Bring the broth and water to a boil in a large saucepan over high heat. Cover and reduce the heat to medium-low to maintain a bare simmer.

Melt the first portion of butter in a Dutch oven over medium heat. Add the onion and salt and cook until the onion is softened and translucent, 4 to 5 minutes. Stir in the garlic and cook until fragrant. Add the rice and cook, stirring frequently, until the edges of the grains begin to turn translucent, about 3 minutes.

Stir in the wine and cook, stirring constantly, until the liquid is fully absorbed, 2 to 3 minutes. Stir in the first large portion of the hot broth mixture. Reduce the heat to medium-low, cover, and simmer until almost all liquid has been absorbed and the rice is just al dente, 18 to 19 minutes, stirring twice during cooking.

Add the second measured portion of the hot broth mixture and stir gently and constantly until the risotto becomes thick and creamy, about 3 minutes. Stir in the Parmesan, then remove the pot from the heat and cover. Let the pot sit for 5 minutes to allow the rice to finish.

Stir in the remaining butter and the lemon juice. Season with salt and pepper to taste. If the texture is too thick, stir in the remaining broth mixture as needed to loosen the consistency before serving. Serve warm while the texture is still fluid and creamy.