Key facts
| Question | Nashville (Metro Water Services) | Charlotte (Charlotte Water) |
|---|---|---|
| First choice | Sanitary sewer cleanout or inside drain to sanitary sewer | Your yard or landscaping, if it soaks in and does not flood neighbors |
| Storm drain | Illegal for chlorinated or salt water and backwash (Metro Code 15.64.205) | Allowed only if chlorine below 0.1 mg/L, no chemicals one week, pH 6 to 9, debris removed |
| Sanitary sewer | Preferred | Last resort, with authorization: 704-336-4407 |
| Saltwater spa | Not to storm drains; salt can damage grass and soil | Never to storm drains |
| Grass or yard | After standing untreated 7 to 10 days, drained slowly on your own property | Slowly, no erosion, no runoff to storm drain, ditch or creek |
| Phone | 880-2420 | System Protection 704-336-4407 |
Sources: Metro Water Services, Guidelines for Draining Your Pool or Spa; Charlotte Water, Filling, Refilling, or Draining a Swimming Pool (August 22, 2026); Nashville Electric Service rates; Duke Energy Carolinas NC Schedule RS.
Nashville: sewer first, grass second
Metro Water Services' guidelines for draining a pool or spa start with the sanitary sewer. Whenever possible, drain into a sanitary sewer cleanout or down a drain inside the house that leads to the sanitary sewer, and filter backwash must go there too. If that is not possible, the fallback is grass: let the water stand untreated for 7 to 10 days to lose its chlorine, then drain it directly onto the lawn, slowly enough that it soaks in without erosion or ponding, and only onto your own property so it does not flood a neighbor's yard. Metro warns that standing water can lead to mosquito problems in as little as 48 to 72 hours and may be a code violation.
The hard line is the storm system. It is illegal in Davidson County to drain filter backwash, saltwater or chlorinated pool or spa water directly into the stormwater drainage system or a creek under Metro Code 15.64.205, because catch basins and ditches lead straight to streams. Salt can also damage plants and soil, so a saltwater spa is best sent to the sanitary sewer. Questions go to Metro Water Services at 880-2420.
Charlotte: yard first, sewer last
Charlotte Water's guidance runs the other way. Its first option is to drain to your yard or a landscaped area, but only if you do not flood or create a nuisance on neighboring property, drain slowly enough to avoid erosion, and let the water soak in rather than reach a storm drain, ditch or creek. The utility notes that most properties are designed to drain off site, so if the water may reach a storm drain, the storm drain rules apply. It suggests telling your neighbors first.
To discharge to a storm drain, all of these must be true: chlorine below 0.1 milligrams per liter, reached by letting the water sit a week without chlorine or by using a chemical dechlorinator, and tested with a pool kit; no other chemicals added for at least a week; pH between 6 and 9; algae and debris strained out; and a slow discharge. Saltwater pools and spas may never go to the storm drain because of high chloride levels. The sanitary sewer is a last resort that requires authorization from Charlotte Water System Protection at 704-336-4407. Filter backwash should go to a landscaped area or the sanitary sewer, never the storm drain, and filters should be rinsed over the lawn with debris put in the trash.
What the refill costs
Charlotte Water bills in Ccf, where 1 Ccf is 748 gallons, and says sewer charges apply up to 16 Ccf. A 480 gallon MyHotTub Victoria is about 0.64 Ccf and a 100 gallon ColdTub about 0.13 Ccf, so a refill is a small line on the bill. Heating it back up is the larger cost. On Duke Energy Carolinas' North Carolina Schedule RS, energy is 12.2603 cents per kWh before riders, effective January 1, 2026, so the Victoria's 4 kW heater costs about 49 cents for each hour it runs. In Nashville, NES lists a 9.254 cent base rate plus a 2.515 cent fuel cost adjustment for September 2026, about 11.8 cents per kWh, or about 47 cents per heater hour for the same tub.
Worked example: a small cold plunge
A 100 gallon ColdTub is the easy case in both cities. In Nashville, carry or pump it to a basement floor drain or laundry sink, which meets Metro's sanitary sewer preference, or let it stand untreated 7 to 10 days and run it slowly across your own lawn. In Charlotte, the same 100 gallons spread slowly over a back lawn that does not slope to the street meets the yard option. If it is a saltwater sanitized hot tub instead, Nashville's answer is the sanitary sewer, and in Charlotte the storm drain is never allowed, so plan a yard drain that truly soaks in or call System Protection.
Related guides
- How to drain a hot tub or cold plunge in Atlanta, Los Angeles, Tampa, Phoenix and Seattle
- 120 V plug and play vs 240 V hot tubs
- Cold plunge water chemistry in Seattle and Portland
- Cold plunge chiller power and cost to run
- Hot tub permit rules by city
Frequently asked questions
Where should I drain a hot tub in Nashville?
Metro Water Services asks you to drain into a sanitary sewer cleanout or an inside drain to the sanitary sewer whenever possible. If you cannot, let the water stand untreated 7 to 10 days and drain it slowly onto grass on your own property.
Is it illegal to drain a hot tub into the street in Nashville?
Draining chlorinated or salt water, or filter backwash, into the stormwater system or a creek is illegal in Davidson County under Metro Code 15.64.205.
Can I drain a hot tub to the storm drain in Charlotte?
Only if chlorine is below 0.1 milligrams per liter, no other chemicals were added for a week, the pH is between 6 and 9, algae and debris are removed, and you drain slowly. Saltwater spas may never go to the storm drain.
Can I use the sewer cleanout in Charlotte?
Only as a last resort, after getting authorization from Charlotte Water System Protection at 704-336-4407. That is the reverse of Nashville, where the sanitary sewer is the first choice.
What about a saltwater hot tub?
In Nashville, send it to the sanitary sewer, since salt water is barred from storm drains and can damage grass. In Charlotte, it may never go to the storm drain, so drain to a yard where it soaks in or get System Protection approval for the sewer.
How fast can mosquitoes start in drained water?
Metro Water Services says standing water can lead to mosquito problems in as little as 48 to 72 hours.
Where does filter rinse water go?
Charlotte Water says not to send filter backwash to the storm drain; rinse filters over the lawn or landscaping and put filter debris in the trash. Nashville's guidelines say backwash must go to the sanitary sewer.
Keep reading
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