It is changed every 90k-100k miles. With the timing belt you should also replace the timing belt tensioner, & the outside belts. You can chose to replace the waterpump as well but does not have to be done with the timing belt. On the Accord you HAVE to change it together but not on the Civics! If you replace the waterpump with the timing belt then you will probably save 1-2 hours of labor But you may not have to replace the waterpum for another year or two. I would suggest when you take your car to the shop tell them you would like the timing belt (along with what's list above) replaced and for them to call you and tell you what the waterpump looks like and their opinion on weather it should be replaced!