Slow drainage in entire house

Quick Answer:

If multiple fixtures (kitchen sink, tubs, toilets) begin draining slowly when you run the dishwasher, it’s usually a sign of a partial blockage in the shared sewer/drain system rather than a broken main pipe. Start by confirming which fixtures are affected, listen for gurgling or smell at vents and the sewer cleanout, then open the cleanout and observe while running water. In many cases you can clear a soft blockage or grease build-up from the cleanout with a heavy-duty drain snake. If flow doesn’t improve or you see wet or soggy spots in the yard or street, arrange a camera inspection and call a professional.

Why This Happens

• Grease, hair, and paper products build up in the main line and slow flow over time.
• Dishwasher discharge can push water faster than a partially clogged main can handle, revealing the problem.
• Vent problems or partial clogs in branches can cause gurgling and slow drainage in several fixtures at once.
• Less commonly, a break or collapse in the public sewer will show as continuous backups and wet spots outside.
• For cases limited to the upper floor, see Partial clog only upstairs. For household-wide partial blockages, see Main sewer line partially clogged.

Step-by-Step What to Do

1. Confirm multiple fixtures are affected

• Run water in the kitchen, a bathtub, and flush a toilet. Note if all are slow at the same time.
• If only one fixture or one floor is slow, the problem may be localized to a branch line.

2. Listen and smell at vents and the cleanout

• Check roof vents (from the ground if safe) for unusual gurgling or odors while someone runs water inside.
• Locate the sewer cleanout (usually a capped pipe near the foundation or at the property line) and smell for sewage when house drains are running.

3. Open the cleanout and observe flow

• With gloves and eye protection, remove the cleanout cap slowly—some pressure or odors may be present.
• Have someone run water in a sink or flush a toilet while you watch the cleanout. You should see steady flow away from the house. Slow, intermittent, or bubbling flow indicates a partial blockage.

4. Use a heavy-duty drain snake from the cleanout toward the street

• A plumber’s auger or heavy-duty drain snake inserted at the cleanout and fed toward the street can break up grease or soft obstructions. Work slowly and pull back to clear debris into the cleanout.
• Do not force rigid tools past resistance that feels like a collapse; stop and call a professional if you meet hard resistance.
• After snaking, run water again and observe the cleanout for improved flow.

5. Inspect the yard or street for external signs

• Look for soggy spots, standing water, or sewage smell in the yard or near the municipal cleanout. These suggest a problem outside the house.
• If snaking doesn’t restore proper flow or you see external wet areas, schedule a camera inspection of the main line to locate the blockage or damage.

What Not to Do

• Don’t keep running the garbage disposal to try to force a slow whole-house drain—this can push more solids and grease into the main line.
• Don’t flush wipes, paper towels, or non-flushable items to cope with slow drainage; they make blockages worse.
• Don’t delay calling a professional when slow drainage continues after clearing the cleanout, you smell sewage, or neighboring homes report similar problems.

When to Call a Professional

• Flow does not improve after you open and clear the cleanout.
• You smell sewage inside or outside the house, or see sewage surfacing in the yard or street.
• Neighbors report the same problem (this can indicate a municipal main line issue).
• You encounter hard resistance while using a snake or see signs of pipe damage during inspection—stop and call a plumber equipped for camera inspection and repair.

Safety Notes

• Wear heavy gloves and eye protection when opening a cleanout and handling debris. Sewage contains bacteria and can be hazardous.
• Work in a well-ventilated area and avoid inhaling sewer gases; if odors are strong, leave and call a pro.
• Do not mix different chemical drain cleaners; they can produce dangerous reactions and will often not clear main-line grease effectively.
• When in doubt, stop and contact a licensed plumber—avoiding DIY escalation is safer than causing injury or pipe damage.

Common Homeowner Questions

• Q: Will pouring hot water and dish detergent clear a main line clog?
  A: Hot water and detergent can help small grease clogs near drains but rarely clear a main-line partial blockage; use the cleanout and a snake for main-line work.
• Q: Is a camera inspection necessary?
  A: Yes if snaking doesn’t work or you see yard wet spots—camera inspection locates the blockage or damage so repairs can be planned.
• Q: Can I open the cleanout myself?
  A: Yes for observation and snaking if you follow safety steps, but stop and call a pro if you smell strong sewage, face hard resistance, or are unsure.

More in this topic

For more related fixes and similar symptoms, see Main Line Partial Clogs.