I have good water pressure but low volume in my house. I have seen presurized water tanks for watering flower in a home depot garden center (store use not for sale). Could I use a water tank and pressurize it so that when full it has set pressure and use it as an acumulator like the tank at home depot?

Volume is by pipe size. Is the low water volume /pressure in the hot and cold both? Are your water lines plastic, copper, black iron and are the 3/8 1/2 3/4? Di you have two floors and is it the same on both? Old homes have will have 3/8 copper for hot in the 50, How old is the house. Just because there is pressure on a well pump gage doesn't mean there good pressure in the other line. Was it good before? Did this slowly start and what is your pressure gage say or are you on city/township water? What is the pressure gage read? Need more info

What's your incoming pressure ? Are you on well or City supply ?

My water line was run in about 1919. I am on city water. I have a small one level house.
I know I need to replace my service line but I was thinking about the portable water tanks that have about 1 psi when empty and you fill them up and the air compresses and it holds the water under pressure. The lines in the house have been replaced but the service line runs under the garage. If the tank filled when water was not in use then supplied water when I flushed the toilet and turned on a faucet I could delay the costly repair of the service line.

QUOTE]my water line was run in about 1919. I am on city water. I know I need to replace my service line [/QUOTE]
You have a galvanized water service that has built up iron oxide,(rust) on the pipe walls restricting the volume entering your home. Adding a pressure tank will give you pressure But uf your drawis greater then the water stored in the tank you'll be in the same situation that you were before. While replacing the water service should be your repair but if yo don't wi8sh to replace at this time you mighgt wish to consider adding a booster pump systom, (see image) Check them out at; Low Water Pressure Pump - Increase Water Pressure (http://www.pressurebooster.com/)
This will assure both a steady volume and pressure flow. Good luck and thanks for rating my answer. Tom