Drain clog or main-line backup?
One slow sink may be local. Wastewater rising in a shower when a toilet flushes is different. Multiple fixtures backing up, gurgling toilets, floor drain overflow, or sewage odor can point to a larger drain, side sewer, septic, grinder, or STEP issue.
What helps narrow it down
Which fixture started it
A kitchen sink, tub, shower, laundry drain, toilet, floor drain, or utility sink each points to a different starting point.
How many fixtures are affected
One fixture can be local. Several fixtures backing up or gurgling at once may need broader drain or sewer attention.
Whether dirty water is present
If sewage or dirty water is visible, avoid contact and pause showers, flushing, laundry, dishwasher use, and sink use.
Mention system clues
If your home has septic, side sewer, grinder, or STEP equipment, say that up front.
Local wastewater context
Olympia has gravity pipes, pressure pipes, pump stations, and STEP systems. Nearby properties may also have septic. The fixture pattern matters because one clogged sink is very different from sewage showing up in several places.
Avoid these risky moves
Do not keep flushing to test it. Do not mix drain chemicals. Do not remove a cleanout cap if wastewater may be under pressure. Keep people and pets away from contaminated water.