Water in a Storm Drain When It Hasn't Rained: What Should You Do?
If water is flowing through a storm drain when it has not rained, document the location and timing from a safe place and ask the appropriate property contact or local stormwater office to review it. Flow alone does not identify its source or prove pollution. Before approving a new drain or pipe replacement, establish what question the investigation needs to answer.
Dry-weather flow is a clue, not a diagnosis
The EPA-hosted Illicit Discharge Detection and Elimination guidance manual explains that dry-weather drainage can come from springs, groundwater seepage, or water-distribution leaks, as well as pollutant sources. It also distinguishes flows that are continuous from those that appear intermittently. Appropriate field investigation and testing, rather than appearance alone, may be needed to establish what is present.
For an owner, the useful distinction is between observing water and naming its cause. A pipe running on a sunny afternoon does not, by itself, establish that the pipe is broken, that a neighbor caused the problem, or that an expensive drainage replacement is needed. Start the conversation with what you actually saw. Leave the explanation open until someone qualified has reviewed the evidence.
Describe the observation so someone else can find it
Give the location a stable name: the inlet beside the rear loading door, the outlet beyond the employee lot, or the channel beside the driveway entrance. Add a property address and a marked photograph. A close-up of water alone is less useful than an overview that shows which structure you mean. Keep the original image and its date rather than forwarding an undated screenshot through several people.
Record whether you saw water moving into the structure, coming out of a pipe, or simply standing below a grate. Those are different observations. Note the time, the most recent rainfall you know about, and whether you have seen the same condition before. If the rainfall history is uncertain, say so. Do not invent a dry period from memory to make the report sound more conclusive.
Use only observations available without opening structures or approaching unknown water. Do not enter a drain, climb down an outlet bank, collect a sample yourself, or lean over an opening to investigate an odor. A safe distant photograph and a clear location are enough to start a report.
Check the operating calendar without assigning blame
Ask the property team whether irrigation, outdoor cleaning, utility work, or other water-related activity was scheduled near the observation time. Request existing schedules or work orders rather than asking employees to recreate an event from memory. If nothing is known, record that as an unanswered question. A coinciding activity is a lead for the reviewer, not proof that the activity caused the flow.
For a commercial property, choose one person to assemble the record. A tenant may have a photograph, the landscape vendor may have a schedule, and maintenance may have a recent service ticket. Bring those pieces together without distributing accusations. Ask vendors to describe their own work and any changes they made; do not ask them to diagnose another company's equipment.
Keep the process proportional. You do not need a week of monitoring before reporting a suspicious condition. If a reviewer requests follow-up observations, agree on who will make them and what information is needed. Avoid sending multiple employees to the same location simply to repeat an unsafe or unhelpful inspection.
Use the water-quality reporting route when appropriate
Nashville's Stormwater Management page explains that stormwater is released to waterways without wastewater treatment. It also provides a specific route for pollution concerns, including an after-hours contact. If you suspect a discharge is polluting a drain, use that reporting route rather than treating the issue only as a request for routine cleaning. For a property outside Nashville, use the responsible local authority's current contact information.
Provide the address, exact observation point, time, photographs, and whether the condition is still occurring. Describe unusual color, material, or odor only if you noticed it safely; do not move closer to obtain more detail. Separate your direct observations from information supplied by another person. Ask for a reference number and the appropriate way to provide additional information.
Do not delay an urgent report while trying to complete a perfect property file. Likewise, do not assume that an online maintenance request is the right response to an immediate emergency. Follow the local authority's instructions for the situation. The purpose of the owner's record is to help the response, not to replace it.
Keep investigation separate from the construction decision
When requesting help, define the first decision in plain language: identify the source of the recurring flow, determine whether the condition needs referral, or evaluate a separately observed drainage defect. Ask the proposed investigator what they can establish, what remains outside their scope, and what written findings you will receive. A quote to replace a pipe should not silently stand in for an explanation of why water is there.
If construction is subsequently recommended, ask how it relates to the findings. Which specific condition will the work correct? Is another party's repair or review needed first? What observation would show that the intended correction worked? These questions help distinguish a justified repair from work that merely changes where the same unexplained water becomes visible.
Milliken lists storm drains, trench drains, under drains, and other drainage and utility services. For a Middle Tennessee property, share the investigation findings along with the location when requesting a construction evaluation. Confirm the scope with the team; do not assume a drainage proposal includes pollution testing, utility ownership determinations, or every outside agency's review.
Close the loop with a short decision record
Before closing the maintenance ticket, record who reviewed the condition, what was established, and what remains unresolved. Include the report reference, any agreed work, and the person responsible for the next step. If no construction is recommended, preserve that conclusion and its basis rather than leaving an unexplained canceled work order.
If the flow appears again, add the new observation to the same record. Do not automatically label it a failed repair or an unrelated new problem. Give the reviewer enough context to compare the events. The practical outcome is an informed next action: a referral, a targeted repair, requested follow-up, or a documented explanation, rather than an expensive guess.
Frequently asked questions
Does clear water mean there is nothing to report?
No. Appearance alone does not establish the source or water quality. Describe the unexplained flow and ask the appropriate contact whether it needs review; do not certify it as harmless yourself.
Should I order a larger drain to handle the extra water?
Not on the observation alone. First ask what is supplying the water and what problem the proposed work would solve. A construction decision should follow the findings, not substitute for them.
What if the water stops before someone arrives?
Keep the dated photographs and notes, explain when you last observed the flow, and provide any relevant operating schedule. Ask the reviewer what additional information would help if it recurs. Do not recreate the discharge for demonstration.