Plumbing bids split cleanly in theory and messily in practice. The usual boundaries (five feet outside the building, fixtures by owner or by contractor, roof drains with plumbing or roofing) are where bids differ most.
Underground work under the slab is the other place to look closely: sawcutting, excavation and backfill are often excluded or carried as unit prices.
Typical scope items
What a complete plumbing bid usually prices, and what to check in each:
| Scope item | What to check |
|---|---|
| Domestic water | Piping from the point of connection, with valves, backflow prevention and insulation if specified. |
| Sanitary waste and vent | Underground and above ground. Check which portions each bid includes. |
| Storm drainage | Roof drains, overflow drains and leaders. Roofing flashes the drains plumbing sets. |
| Fixtures and trim | Furnished and installed, installed only (owner furnished), or excluded. |
| Water heaters and equipment | Note the equipment carried against the basis of design. |
| Natural gas piping | Sometimes with mechanical. Make sure it is carried once. |
| Testing, flushing and disinfection | Usually included; confirm it is stated. |
Common exclusions and qualifications
Not every exclusion is a problem. Some are fair because the work belongs elsewhere. The ones below are where plumbing bids most often differ, so read them against the other bidders.
| Often excluded | Why it matters |
|---|---|
| Site utilities beyond a set distance from the building | Commonly excluded beyond five feet. The sitework bid needs to pick it up. |
| Tap, impact and meter fees | Often excluded. Carry them as an allowance if no bid includes them. |
| Sawcutting, excavation and backfill | Under-slab work in an existing building is a common exclusion. |
| Rock excavation and dewatering | Usually excluded or carried as a unit price. |
| Fixtures furnished by the owner | Fine if that is the plan; check the bid installs them. |
| Fire protection | Sprinklers are normally a separate trade package. |
| Kitchen and process equipment connections | Frequently excluded or limited to stub-outs. |
Alternates to watch
- Fixture upgrades or substitutions
- Tankless or alternate water heating equipment
- Additional fixtures or restrooms
Line alternates up by the numbers on your bid form, keep add and deduct straight, and treat an unpriced alternate as a question, never as zero.
Unit prices and allowances to compare
- Sanitary or water line, per linear foot
- Rock excavation, per cubic yard
- Sawcut and patch slab, per linear foot
- Utility fee allowance
Compare rates only where the units match, and note any quantity already included in the base bid.
Where plumbing meets other trades
Gaps and double counts happen at the edges. Read these packages together:
- Sitework (utilities outside the building)
- Roofing (roof drains and overflows)
- Mechanical (gas piping, condensate)
- Concrete (sawcutting and slab patching)
How Bidtab lays out plumbing bids
Upload each bidder's PDF to one project for the package. Bidtab reads every bid and shows, side by side and in the order you uploaded them:
- each base bid, as stated;
- alternates aligned by number and description, with add or deduct for each bidder;
- a scope row for each item the bids address, with every bidder marked Included, Excluded, Qualified or Not stated;
- allowances and unit prices, with their units;
- each bidder's exclusions and qualifications as written;
- open questions where a bid is silent on an item other bidders addressed, where a figure isn't printed on the page it came from, or where line items don't add up to the total.
Every figure shows the page and words it came from, and the whole comparison exports to an Excel workbook. Bidtab doesn't rank bidders or price excluded scope; those calls stay with you. See the sample project (a roofing package) for the layout.