how do i drain water fom my back patio into my yard?
I have a low spot in my back patio, but water collects there because my lawn grass lines the edge of the concrete patio. I heard, once, of a way you can create an underground drainage pool with differing sizes of gravel. Has anybody heard of this?
Your are referring to a French drain which is a hole filled with gravel which collects and dissipates the water. They work well in non clay soils. The size and depth of the drain is determined by the surrounding soil condition and the amount of water you are trying to control.
If your patio is small enough, it might just be best to re-pour it with a high side at the foundation of your house and a low side where you want the water to drain. When I was pouring patios and doing masonry contracting, I always put two tapers in my patios, with taper(slopes) running not only away from the house, but off to the sides and away from the house as well. If you cannot re-pour your patio, flood your patio with water, find the deepest spot, cut a 16″ x 16″ hole at that point vertically through the patio, dig a at that spot, and dig as deep a hole as you can in that cut-out area. Fill it with crushed rock, and purchase a floor drain and install it over the crushed rock so that the top of the floor drain is just a little below the exisitng surface of the patio. Secure that in place with concrete.