Boston Water Pressure Calculator

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Boston Water Pressure Calculator

Estimate the static water pressure at your location in Boston's water distribution system based on elevation, service zone, and pipe height. Uses BWSC (Boston Water and Sewer Commission) distribution standards.

Ground Elevation (feet above sea level)

Boston ranges from sea level to ~330 ft (Bellevue Hill). Average street level ~20–80 ft.

Service Pressure Zone

Low Zone (Downtown, South Boston, East Boston) — HGL ~200 ft Mid Zone (Back Bay, Roxbury, Jamaica Plain) — HGL ~280 ft High Zone (West Roxbury, Hyde Park, Roslindale) — HGL ~360 ft Booster Zone (Elevated areas, hilltops) — HGL ~440 ft

HGL = Hydraulic Grade Line (pressure head maintained by BWSC reservoirs/pumps).

Service Entry Height Above Ground (feet)

Typically 1 ft for basement entry; use floor height for upper-floor fixtures.

Estimated Friction / Dynamic Loss (psi)

Typical residential service line loss: 3–10 psi. Increase for long or older pipes.

Calculate Pressure

Enter values above and click Calculate.

function bosCalc() { var resultDiv = document.getElementById('bos-result');

var elevation = parseFloat(document.getElementById('bos-elevation').value); var pipeHeight = parseFloat(document.getElementById('bos-pipe-height').value); var frictionLoss = parseFloat(document.getElementById('bos-friction-loss').value); var zone = document.getElementById('bos-zone').value;

// --- Input Validation --- if (isNaN(elevation)) { resultDiv.innerHTML = '⚠ Please enter a valid ground elevation.'; return; } if (elevation 330) { resultDiv.innerHTML = '⚠ Elevation must be between -10 and 330 ft for Boston.'; return; } if (isNaN(pipeHeight) || pipeHeight 20) { resultDiv.innerHTML = '⚠ Service entry height must be between 0 and 20 ft.'; return; } if (isNaN(frictionLoss) || frictionLoss 60) { resultDiv.innerHTML = '⚠ Friction loss must be between 0 and 60 psi.'; return; }

// --- Hydraulic Grade Line by Zone (feet above sea level) --- var hglMap = { low: 200, mid: 280, high: 360, booster: 440 }; var hgl = hglMap[zone];

// --- Total elevation of service point (ft above sea level) --- var serviceElevation = elevation + pipeHeight;

// --- Pressure Head (ft of water) --- // Static pressure head = HGL - service point elevation var pressureHeadFt = hgl - serviceElevation;

// --- Convert feet of water to psi: 1 psi = 2.3077 ft H2O --- var FT_PER_PSI = 2.3077; var staticPressurePsi = pressureHeadFt / FT_PER_PSI;

// --- Residual (dynamic) pressure after friction losses --- var residualPressurePsi = staticPressurePsi - frictionLoss;

// --- BWSC Standards --- // Minimum: 40 psi at service connection (BWSC policy) // Maximum: 80 psi recommended; >100 psi requires PRV var MIN_PSI = 40; var MAX_PSI = 80; var PRV_THRESHOLD = 100;

// --- Status Assessment --- var status = ''; var statusColor = ''; if (pressureHeadFt PRV_THRESHOLD) { status = '⚠ Pressure exceeds 100 psi. A Pressure Reducing Valve (PRV) is required by code.'; statusColor = '#c0392b'; } else if (staticPressurePsi > MAX_PSI) { status = 'ⓘ Pressure above 80 psi. A PRV is strongly recommended to protect fixtures and appliances.'; statusColor = '#e67e22'; } else if (residualPressurePsi '; html += 'Hydraulic Grade Line (HGL)' + hgl.toFixed(1) + ' ft above sea level'; html += 'Service Point Elevation' + serviceElevation.toFixed(1) + ' ft above sea level'; html += 'Pressure Head' + pressureHeadFt.toFixed(1) + ' ft of water'; html += 'Static Pressure' + staticPressurePsi.toFixed(1) + ' psi'; html += 'Friction / Dynamic Loss- ' + frictionLoss.toFixed(1) + ' psi'; html += 'Residual Pressure at Fixture' + residualPressurePsi.toFixed(1) + ' psi'; html += ''; html += '' + status + '

';

// PRV note if (staticPressurePsi > MAX_PSI && staticPressurePsi

#### Formula

Static Pressure (psi) = (HGL − Service Point Elevation) ÷ 2.3077

Where:

Pressure zones reflect BWSC's tiered distribution network fed by the Chestnut Hill, Spot Pond, and Fells Reservoirs via the MWRA supply system.

#### Assumptions & References

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References

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