What's probably going on right now
If you're reading this, odds are your water heater is making a sound it didn't used to make. A ticking or popping noise when it heats up. Maybe the hot water runs out faster than it used to, or it comes out a little rusty at the start. None of that means the unit is simply old and worn out. In the Ozarks, it almost always means something else entirely: the water itself.
Why Nixa's water is harder on tanks than most places
Nixa and the surrounding area sit on limestone and dolomite bedrock, and the water drawn from local wells and the regional supply carries a heavy load of dissolved calcium and magnesium. That's hard water, and it doesn't stay dissolved once it hits the inside of a hot tank. Heat drives those minerals out of solution, and they settle as scale on the heating element and along the bottom of the tank.
This is the actual reason most tanks in this area fail years before they should. A water heater rated for ten or twelve years of service can be done in six or seven if scale builds up unchecked. The manufacturer's age estimate assumes reasonably soft water. Nixa doesn't have that, so the clock runs faster here than the sticker on the tank suggests.
More on this from Why Hard Water And Not Age Ends Most Tanks.
What that buildup actually does
Scale on the bottom of the tank acts like a layer of insulation between the burner or element and the water it's supposed to heat. The unit works harder and longer to reach the same temperature, which shows up as a higher gas or electric bill before it shows up as an obvious problem. That popping and rumbling sound is water trapped under the mineral layer, boiling and escaping through it. It's not the tank settling with age. It's sediment cooking.
Over time that same sediment clogs the drain valve, coats the thermostat sensor so it reads temperatures wrong, and in tank-style units can eventually crack the glass lining that protects the steel underneath. Once that lining fails, the steel corrodes from the inside and a leak is just a matter of time.
What you can check yourself
Once or twice a year, drain a few gallons from the valve at the bottom of the tank into a bucket. If what comes out is cloudy, gritty, or has visible chunks of white or tan sediment, you've got scale buildup, and it's worth draining and flushing the whole tank. This is also a good time to look at the water around the base of the unit for any sign of slow leaking, which often starts at the drain valve or the fittings on top.
Check the temperature and pressure relief valve by lifting its lever briefly and letting it snap back. It should release a little water and then stop drying. If it won't close, or if it's been dripping steadily at the pipe, that's a part that needs replacing, not something to leave.
Many homes in the Nixa and Christian County area, especially in the newer subdivisions built over the last fifteen years, were plumbed with the standard glass-lined tank heaters that are more sensitive to scale than a tankless unit would be. If your house is one of the older farmhouses or ranch homes converted or added onto over the decades, check the age sticker, because mismatched replacement units are common after remodels and you may not know how old the actual heater is.
Where this stops being a DIY job
Draining a few gallons for a sediment check is easy and safe for most homeowners to do. A full flush of a heavily scaled tank is a different matter. If the drain valve is clogged with sediment and won't fully open, forcing it can snap the valve off and empty the tank onto your floor fast. If the unit is gas-fired and you smell gas at any point, or the pilot won't stay lit, that's not a sediment problem to troubleshoot on your own.
The bigger sign that it's time to call for water heater repair rather than keep flushing it yourself is rust-colored water that doesn't clear after running the tap for a minute, a tank that's visibly leaking from the seams rather than the fittings, or an element that fails repeatedly even after a flush. At that point the scale has likely already done damage inside the tank that cleaning won't reverse, and a professional can tell you honestly whether you're looking at a repair or a replacement before more water ends up on your floor instead of in your shower.