Instructions
Click the "Build" icon in "The Sims 3" control panel in the lower left of the screen.
Click the "Pool" icon and select the option to build a pool. Click the area where you want to place your hot tub and drag the cursor over the area where you want the hot tub to cover.
Click the "Raise Terrain" icon, then click the edge of the pool. Drag the edge of the pool up eight clicks. The bottom of the pool will also rise.
Press the "Ctrl," "Shift" and "C" keys at the same time to make the cheat box visible. Enter "constrainfloorelevatio false" in the cheat box and press the "Enter" key.
Click the "Level Terrain" icon, then click the edge of the pool. Drag the cursor over the pool until the bottom of it is highlighted in green. Ensure the entire bottom of the pool is covered with the green box.
Click the "Level Terrain" icon again and drag the corners of the raised pool down to the level of the ground. The pool should be completely level with the ground surrounding it. If not, continue to drag each part until it is.
Click the "Buy Mode" icon, then click the "Furniture" icon. Review the style of sofas available to put in your hot tub.
Click the sofa you want to use, then click the area of the pool in which you want to place it. Place the sofa against the wall of the inside of the pool to make it look like it is part of the pool.
Click the "Build Mode," then click the "Flooring" icon. Review the flooring available and select one to place around the outside of the pool to add style to your hot tub. Click "Live" to start the game again.