In Out Plumbing is included in this directory under Residential Plumbing for Ontario, California. The listing is a starting point for discussing the specific work you need and checking current availability.
For intermittent plumbing problems, note when they occur and whether changes in usage make symptoms better or worse. For this type of request, the discussion may involve fixture connections, shutoff valves, visible supply lines, and household drains, depending on the property and the symptoms. Avoid assuming a single symptom proves the need for replacement; ask how the diagnosis will be made.
Before authorizing work, ask for a written scope and clarify diagnostic charges, parts, cleanup, and any permit or warranty requirements.