body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
margin: 0;
padding: 0;
}
.calculator-container {
max-width: 800px;
margin: 20px auto;
background: #fdfdfd;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-header {
text-align: center;
margin-bottom: 25px;
border-bottom: 2px solid #005eb8; /* Water blue */
padding-bottom: 15px;
}
.calc-header h2 {
color: #005eb8;
margin: 0;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 768px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.calc-section {
background: #f0f7ff;
padding: 15px;
border-radius: 6px;
border: 1px solid #dbeeff;
}
.calc-section h3 {
margin-top: 0;
font-size: 1.1em;
color: #003d7a;
border-bottom: 1px solid #cce4ff;
padding-bottom: 8px;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
}
.form-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.form-group .help-text {
font-size: 0.8em;
color: #666;
margin-top: 3px;
}
.btn-calculate {
display: block;
width: 100%;
background: #005eb8;
color: white;
border: none;
padding: 15px;
font-size: 1.1em;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
margin-top: 20px;
transition: background 0.2s;
}
.btn-calculate:hover {
background: #004a94;
}
.results-box {
margin-top: 30px;
background: #fff;
border: 2px solid #005eb8;
border-radius: 8px;
padding: 20px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
}
.result-value {
font-weight: bold;
font-size: 1.1em;
}
.highlight-savings {
background-color: #e6fffa;
color: #007a5e;
padding: 15px;
text-align: center;
border-radius: 4px;
margin-top: 15px;
font-weight: bold;
border: 1px solid #b2f5ea;
}
.highlight-cost {
background-color: #fff5f5;
color: #c53030;
padding: 15px;
text-align: center;
border-radius: 4px;
margin-top: 15px;
font-weight: bold;
border: 1px solid #fed7d7;
}
.content-article {
max-width: 800px;
margin: 40px auto;
padding: 0 20px;
}
.content-article h2 {
color: #2c3e50;
}
.content-article h3 {
color: #34495e;
margin-top: 25px;
}
.content-article ul {
padding-left: 20px;
}
.content-article li {
margin-bottom: 10px;
}
Understanding Water Rates in the UK
Calculating your water bill in the UK can be complex because charges depend heavily on whether you have a water meter or pay based on your home's Rateable Value (RV). This calculator helps you estimate your potential savings by switching to a water meter.
1. Unmetered Charges (Rateable Value)
If you do not have a water meter, your bill is not based on how much water you use. Instead, it is based on the Rateable Value of your property. Rateable Values were assessments made by the Valuation Office Inland Revenue prior to 1990 regarding the rental value of a property.
The unmetered formula is generally:
- Rateable Value (£) × Rate per £ + Standing Charge
Because these values are outdated, a single person living in a large house with a high RV often pays significantly more than they would on a meter.
2. Metered Charges (Pay as You Use)
If you switch to a meter, you pay for exactly what you use. The unit of measurement is the cubic metre (m³), which equals 1,000 litres.
The metered formula is:
- Units Used (m³) × (Water Rate + Sewerage Rate) + Standing Charge
The average person in the UK uses approximately 140 to 150 litres per day (roughly 50-55 m³ per year). This calculator uses an average of 55 m³ per person per year to estimate your usage.
Should I Switch to a Meter?
The general "Rule of Thumb" in the UK is: If you have more bedrooms than people in your house, you should probably switch to a meter.
For example, a couple living in a 4-bedroom house will likely have a high Rateable Value but low actual water usage. Switching could save hundreds of pounds annually. Conversely, a large family in a small flat might be better off staying on unmetered rates.
Important Terms
- Standing Charge: A fixed annual fee that covers billing and customer service costs. This applies to both metered and unmetered customers.
- Sewerage Charge: The cost to take wastewater away from your home. This is often calculated based on 90-95% of the water you consume (allowing for water drunk or used in the garden).
- Surface Water Drainage: If rainwater drains from your property into the public sewer, you pay a fee for this. It is often included in the standing charge or sewerage rate.
Note: Water and sewerage rates vary by region (e.g., Thames Water, Severn Trent, United Utilities). Check your latest bill for the exact pence-per-pound or pence-per-cubic-metre rates.
function calculateWaterBill() {
// 1. Get Inputs for Unmetered
var rv = parseFloat(document.getElementById('rv').value);
var rvRate = parseFloat(document.getElementById('rvRate').value);
var unmeteredStanding = parseFloat(document.getElementById('unmeteredStanding').value);
// 2. Get Inputs for Metered
var householdSize = parseInt(document.getElementById('householdSize').value);
var waterRate = parseFloat(document.getElementById('waterRate').value);
var sewerageRate = parseFloat(document.getElementById('sewerageRate').value);
var meteredStanding = parseFloat(document.getElementById('meteredStanding').value);
// Validation
if (isNaN(rv) || isNaN(rvRate) || isNaN(unmeteredStanding) ||
isNaN(householdSize) || isNaN(waterRate) || isNaN(sewerageRate) || isNaN(meteredStanding)) {
alert("Please fill in all fields with valid numbers.");
return;
}
// 3. Logic: Unmetered Calculation
// Formula: (RV * Rate) + Standing Charge
var totalUnmetered = (rv * rvRate) + unmeteredStanding;
// 4. Logic: Metered Calculation
// Assumption: Average UK usage is approx 55 cubic meters per person per year
// Some sources say 142 liters/day = 51.8 m3/year. We will use 55 to be safe/conservative.
var avgUsagePerPerson = 55;
var totalUsage = householdSize * avgUsagePerPerson;
// Cost = (Usage * (Water Rate + Sewerage Rate)) + Standing Charge
var totalMetered = (totalUsage * (waterRate + sewerageRate)) + meteredStanding;
// 5. Calculate Difference
var savings = totalUnmetered – totalMetered;
// 6. Display Results
document.getElementById('results').style.display = "block";
document.getElementById('resUnmetered').innerText = "£" + totalUnmetered.toFixed(2);
document.getElementById('resUsage').innerText = totalUsage.toFixed(0) + " m³";
document.getElementById('resMetered').innerText = "£" + totalMetered.toFixed(2);
var recElement = document.getElementById('resRecommendation');
if (savings > 0) {
recElement.className = "highlight-savings";
recElement.innerHTML = "You could SAVE approximately £" + savings.toFixed(2) + " per year by switching to a meter.";
} else {
recElement.className = "highlight-cost";
var extraCost = Math.abs(savings);
recElement.innerHTML = "Switching to a meter might COST you an extra £" + extraCost.toFixed(2) + " per year.";
}
}