Hey I have a 1999 SVT with 50,xxx and I haven't changed the water pump, do i need to??

If so, why?

Thanks,
Joe

1999 Contour SVT ~ Black w/Tan Current Mods: Fog light rewire, 20% Tint, SVT Banner,Rockford Fosgate RFX-8340, 2-12" Bostwick SPL Subs & Audiobahn 600x2 Future Mods: Knauberizing it, lowering