My shop floor is 3 1/2 inches thick concrete that was poured on red clay that was packed hard and allowed to settle for a couple of years.
Only crack in the floor is where we stopped pouring one day and started pouring again days later.
Has had plenty of heavy tractors, trucks and other equipment on it.

Now to my question.
I am putting in a bathroom and a sewage pump to pump to my septic tank.
Wife has wanted a bathroom in my shop for years as her sewing room is off the back of the shop.
I need to cut a square hole in it about 18x18 inches and 2 cuts about 6 feet long to put in a sewer line and water line.
Both will be in the same cut about 4 inches wide.
I really don't want to rent a gas powered concrete saw.
I have several old circular saws that run and will rig up a large shop vac to collect some dust.
Will the concrete blades from Lowes or Home Depot do the job?
I know I will have to use a big hammer to break the concrete out of the cuts.
There is no steel wire or rod in the floor.
Thanks, Richard in NW SC

Check your local codes. Most places do not permit a sewer and domestic water line in the same trench. High possibility of contamination. Pipes have to be separated both vertically and horizontally a certain distance. Renting a concrete saw is the way to go, as well as a little water to cut down the dust. Clean it up when wet, as already said, and don't let the "goop" dry on any surfaces; it is difficult to remove. zuhnc

Just me. But I would never cut a trench in concrete to install a sewer line. Instead elevate a platform type structure to build the bathroom on. Then you would just need to cut a hole for sewer and water line under the slab. Having it elevated gives you flexibility if you wish to add a shower, washer etc later on.

We have used a garden hose and did not even hook it up to the saw,just run it on the concrete.

Thanks for all the advice.
I called Sunbelt Rentals and they will rent me a gas powered saw for $73 for 24 hours.
Said 2 $9 blades should do what I want. Will get 3 to be sure.
Saw will cut 4 1/2 inches deep.
Will get it when I get a few more things ready.
Richard

Renting a gas power hand held saw is what I have used.

It is not cheap, you have to buy the blade or blades depending on how much cutting you have to do.

The choice is several abrasive blades $$$, or one diamond blade $$$$$$!

I've always went with the abrasive blades.

Keep it wet, wear a dust mask, be ready to clean up a mega mess. Avoid letting it splatter on the walls or surroundings, very difficult to clean up once dry.

Richard, I bought a 7 inch diamond blade from Lowes recently to cut a mausoleum door for the church cemetery. Door is 30"x 32"x 2" thick. I had to cut about 1/2" off of two sides. I only sawed about 1/2" deep at a time and made about 5 cuts total for each side and did not use any water, though I had planned to. It was easy on the saw and the blade was only warm. I believe I could have cut more on each pass and still have been OK, especially with water. The blade was cost around $40 but they had some that cost less. I doubt that a 7 or 7 1/4 blade on a circular saw would go deep enough for your floor.

I hope you are doing well.

Garry

Thanks Garry.
We are well, just getting older.
Since we now have some friends about 20 miles from you, I may be coming by someday when all this mess is settled down.
Richard

At my work we use Stihl gas powered saws all the time for cutting concrete along with large self propelled saws. The Stihl saws we use have a hook up for water. Concrete dust is a big issue with OSHA here because of silicosis. I know you don’t want to rent a saw, but if I was you I would. Gas saw with a good diamond blade and water. I could make your cuts in probably around 15 minutes. Yes there will be the “sludge “ from using water, but no dust. That dust is very fine, and will be everywhere in your shop even if you try to hook a vacuum to it. I actually own my own Stihl saw and would do it for lunch if you were closer !

If your going to cement the floor back in, you could just break the floor up with a hammer drill.

Rich, rent a electric concrete saw with the diamond blade that has a water hook up, no dust & the diamond blade & water makes a nice cut. The Cut N Break Saws work best, as they make two paralleled cuts, & you use the tool that comes with to break out the narrow strip, which allows you to break out the larger sections. If you only make a single cut, you'll never get the cut concrete out, no room to extract ! Alan, Contractor/Builder

Electric saws do take a bit of amp draw so you need good power. Cut-n-Breaks work nice if you can find them to rent and don’t seem to have the amp draw. Gas saws are a sure bet, but dirty. Water works best with all the them.

Rent an electric saw.

The 7 1/4 diamond blades in a strong saw will cut just like the big ones only not as deep. I run one in an older black and decker worm drive from time to time. Makes a lot of dust. Best dust control is water. If you have to stay dry, put a drywall bag in the shop vac, but you will still have a fog of dust in the air.

You can also rent bigger electric saws, same size blade as the gas ones.