Drain your water tank annually.

http://www.homewarrantyreviews.com/home-maintenance-basics-video

Water tanks are something we rarely think about until you wake up to a cold shower. Here is a tip to extend the life of your water heater substantially.
First consider the temperature setting, mine sits at about 120 degrees but I don't have 3 girls in the house either, the dishwasher heats water to the temp required to sterilize dishes so what you need is enough hot water to shower, wash and clean generally. With 50 gallons of hot water (the label on your tank will tell you how much) you likely don't need to have it near scalding at 150 degrees. Every degree you move it up the more heat and energy is lost all day while it sits there waiting for you to draw it down. Why bother to have it so hot you need to mix a lot of cold in? Insulating pipes is a good idea but a challenge to get it done right. Copper pipes in a crawl space or slab are going to be cold. Heating them to 120 is better than 150 since they will cool off shortly anyway.
The second step here is to drain your tank annually to clear all the sediment buildup that will ultimately kill the tank and cost you $1000.00 or more. I see tanks 20 years old working well and I've seen 5 year old tanks being changed out due to lack of care or regular maintenance (turn it down when you go out of town or if the gas is off) The link provided will give you a series of steps to take when you want to drain that tank. Allow lots of time to let it drain all the way so turn it down, go and shower or use up the water and then drain what warm water remains on a saturday morning. Turn the water off that enters the tank after you have used what you need or there will be no pressure. Water tanks today are stainless steel inside and most of our pipes are copper now so rust isn't the big issue, what you need to clear is all the chemical residue or particulates in the water that build up over time. Flushing isn't requires just drain and refill once a year to maintain the water quality hot or cold.
One last note, in an earthquake you have 50 gallons of water waiting for you in this system, attach a hose or fill a jug but use it wisely you may need it for a week. Placing garbage bags in the toilet to be thrown away uses less water but the toilet will flush if you fill the tank at the back.
If you don't have an earthquake preparedness kit in place you need to work on it, I will pull a list together next week and post it here.