I wouldn't put any water under there because of potential mould issues (in fact, there looks like there's a bit of mould already -- is there?). You could tile the bottom of it and put a strip of LED lights under the glass. What did you have in mind when you initially thought of the idea?

I suggest you follow the step-by-step guide for creating storage cabinets under the bathroom sink. Take proper measurements - Measure the available available space in height, width and height. Cut Plywood to size - With a circular saw and framing square, cut all the required pieces out. You can use a sliding compound saw as an alternative. Attach the base and sides - Start assembling the sink cabinets by placing the bottom piece of plywood sheet on a flat surface. Attach the back and top boards - Place the plywood sheet for the top part of the cabinet and attach wood screws to connect it to both the sides. Turn the back faces of the cabinet upwards. Keep the back piece over the structure and fix it into place with wood screws. Attach shelves - Place the cabinet in an upright position to install the shelves. Slide a shelf into the structure so it is flush against the back. Attach door - Keep both hinges of the door on the same side of the plywood sheet. Drill them using wood screws into place. Now keep the door over the cabinet structure, extend the hinges to one of the side panels and fix them to make them secure. Fix a hasp closure on the other side of the door, placing it in the center of the hinges.

I did a house with nine bathrooms and it was so much fun. For the master bed we had his and hers separate ensuite bathrooms, so hers was feminine and victoruan; it even had a chandelier! His was white with a red shower wall and a blue and white border tile. The counter was tiled with red. It was a very cheerful little bathroom. The daughter's batH was blue and white, the border tiles and washbasin were Chinese themed. A very pretty bathroom. The two guest bathrooms were yellow and cream with hand painted sunflower accent tiles. One powder room was yellow and white, the other was beige with orange and green accents. It had a very whimsical washbasin with a hand painted frog inside. The pool house also has two bathrooms, more basic, mostly cream with wood accents. The colour comes from the stack of towels, red, blue, orange, lime green and yellow.

Hello ramarao, This is the outline furniture plan of your given layout. Some measurements needs to be rechecked. If you can do some structural changes like the door from the drawing room to some other room and few minor changes, we can plan it better.