New SH customers: first fill $2.99/gal — mention it at the counter. 5-gallon minimum, both locations.
SH pricing — same at both locations
| Fill | Price | Notes |
|---|---|---|
| Per gallon — under 55 gallons | $4.29/gal | 5-gallon minimum · your tank, tote or drum |
| Per gallon — 55 gallons and up | $3.79/gal | The bulk rate kicks in automatically at 55 |
| 5-gallon carboy (empty container) | $28 | Buy the carboy once, refill it forever |
We fill by the gallon (5-gallon minimum) — no drum surcharges, no container games. Bring anything clean that holds chlorine; if you need a container, carboys are $28 and yours for good. SH pricing moves with the chemical market — call 540-300-3122 to confirm today's rate before a big fill.
Why freshness is everything with SH
Sodium hypochlorite degrades from the day it's made — heat and time knock percentage points off fast. Buy "12.5%" that's been sitting a month and you're really spraying 9–10%, then wondering why the algae didn't die. We turn over more than 10,000 gallons a month, every delivery is tested at 12.5%, and the batch date is posted at the fill station. Ask to see it — we like being asked.
How bulk fill works
- Pull up. Fill lane at both stores — rigs, trailers and totes fit fine.
- We fill and meter. Your tank, our hose, exact gallons on the ticket.
- Pay and go. Most fills are in and out in under 10 minutes. Contractor accounts charge to net terms.
Pool service routes
The same fill lane works for pool routes: straight 12.5% sodium hypochlorite — no additives — batch-tested, with the date posted at the station, into your carboys or drums at the bulk rate. Liquid chlorine loses strength sitting on a shelf the same way it does in a warehouse, so route trucks fill fresh here instead. Per the product label, call for pool-use instructions: 540-300-3122.
The pro's SH guide
Strength, and why it drops
Sodium hypochlorite ships at 12.5% and starts losing strength immediately — heat is the enemy, then time, then sunlight. A carboy left in a hot truck bed loses percentage points in weeks; a drum in a cool, shaded corner holds far longer. Buy what you'll use in the next few weeks, keep it out of the sun, and refill fresh rather than stretching an old batch with a stronger mix.
Typical mix strengths at the surface
| Job | SH at the surface | Notes |
|---|---|---|
| Vinyl and painted siding | about 1% | Dwell, then rinse thoroughly; surfactant for cling |
| Brick, stucco and stone | 1–2% | Pre-wet, keep it wet, rinse well |
| Asphalt shingle roofs | stronger — several percent | Roof surfactant, low pressure, no rinse on the shingles |
| Concrete and flatwork | 1–3% | Post-treat after surface cleaning for organic staining |
These are starting points, not rules — surface condition, temperature and dwell time move them. The SH mix calculator converts a target percentage into gallons for your tank and injector ratio.
Storage and safety basics
- Cool, shaded, closed container; vented caps on carboys. Never a sealed metal drum.
- Never mix SH with acids or ammonia-based cleaners — both release toxic gas.
- Gloves, eye protection and SH-rated clothing; rinse skin and pre-wet plants, then neutralize runoff.
- Chlorine-rated pumps, hose and fittings only — SH eats brass and ordinary seals.
12.5% SH versus pool chlorine
Pool liquid chlorine is commonly sold at 10% and sometimes carries additives; soft-wash pros use straight 12.5% so the mixing math is predictable and the surfactant behaves. Ours is straight sodium hypochlorite, batch-tested at 12.5%, with no additives — which is why pool service routes fill here too.
What crews pair with it
Surfactants (Cherry Surf, Lemon Dancer), the SH mix calculator for target percentages, downstream injectors and check valves, and neutralizer for plants — the full shelf is on the pressure washing chemicals page. The counter will talk you through a house-wash mix in two minutes.
FAQ
Where can I buy 12.5 sodium hypochlorite near me?
Capital Pressure Supply fills fresh 12.5% SH at 11900 Livingston Rd Ste 139 in Manassas (Mon–Fri 8–6, Sat 9–3) and 10817 Courthouse Rd in Fredericksburg (Mon–Fri 8–4, Sat 9–3). $4.29/gal under 55 gallons, $3.79/gal at 55+, 5-gallon minimum — bring any clean tank or tote, or buy a $28 carboy once and refill it.
How much does sodium hypochlorite cost per gallon?
At Capital Pressure Supply: $4.29 per gallon under 55 gallons, $3.79 per gallon at 55 gallons and up, with a 5-gallon minimum fill. Pricing is the same at the Manassas and Fredericksburg locations.
Is pool chlorine the same as SH for pressure washing?
Pool liquid chlorine is usually 10% and often has additives; soft wash pros use fresh 12.5% SH for predictable mixing. Our SH is straight sodium hypochlorite, batch-tested at 12.5% — which is exactly why pool service companies fill here too.
What percentage should I mix for a house wash?
Most vinyl house washes land around 1% SH at the surface; roofs run stronger. Use our SH mix calculator for exact gallons of SH, water and surfactant for your tank.
Where can crews near Sterling, Ashburn or the Dulles corridor get SH?
Our Manassas fill lane at 11900 Livingston Rd is the closest fresh-SH walk-up for most of the Dulles corridor — about 25–30 minutes from Sterling, Ashburn, Chantilly and Herndon via Route 28, and it opens at 8am with Saturday hours.
Do you sell liquid chlorine to pool service companies?
Yes — pool route companies fill the same batch-tested 12.5% sodium hypochlorite at the bulk rate, straight product with no additives and the batch date posted at the station. Bring carboys or drums to the Manassas or Fredericksburg fill lane. Per the product label, call 540-300-3122 for pool-use instructions.
Do you deliver?
We're walk-up fill first — that's how the price stays down and the product stays fresh. Ask the counter about drum orders and volume arrangements for big weekly users.