To Hindu and Buddhist religions this flower is a symbol of wakening to the religious reality of life. Between the two religions the meaning varies somewhat differently but both religions place high importance on the lotus flower.
To the more modern tattoo admirers the meaning simply refers to representing "life in general". Just as the beautiful lotus flowers starts it growth in the bottom of a muddy pod into something of great beauty as people we may also grow and evolve into something more beautiful as well. Thus the symbol represents our struggle in life of growth and change.
For those that may have gone though a rough time in their life and overcame it seems to be the ones who have chosen this flower design as a personal symbolic reference to themselves. Just as the lotus flower started at the bottom of that nasty pond it journeyed forth and evolved into something of magnificent beauty.
The Lotus flower tattoo design is often placed or harmonized with a Koi fish. Many times in a Koi fish pond can be found the beautiful lotus flower, perhaps why they are often creatively designed and intertwined together.